3DTH5CM1LD 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 


A   HAND-BOOK   OF 


PRECIOUS  STONES 


M.  D.  ROTHSCHILD 


THIRD   THOUSAND 


NEW    YORK    &    LONDON 

G.     P.     PUTNAM'S     SONS 


1901 


COPYRIGHT   BY 

M.  D.  ROTHSCHILD 


TCbe  imfcfterbocfesr  preas,  *tew  Jffotk 

Electrotyped  and  Printed  by 
G.  P.  Putnam's  Sons 


Geology 
Library 

TS 

CONTENTS. 

1  $  45 
I  o   7<^ 

PAGE 

What  are  Precious  Stones  ? 

7 

Physical  Characters  — 

Crystallization  .... 

10 

Cleavage  ..... 

Fracture    ..... 

ii 

Optical  Properties  — 

Refraction          .... 

12 

Polarization  of  Light 

13 

Pleiochroism      .... 

14 

Colors      .'        .         . 

15 

Lustre      ...... 

17 

Streak      

18 

Hardness          ..... 

19 

Specific  Gravity        .... 

21 

Weight             

27 

Fusibility          

28 

Magnetism        ..... 

Transparency            .... 

30 

Electricity         

Cutting  and  Polishing 

32 

Diamond           ..... 

35 

Corundum         ..... 

39 

The  Ruby        

Fancy  Sapphires       .... 

44 

1059098 


11  CONTENTS. 

PAGE 

Star  Sapphires          ......  45 

Spinel 46 

Beryl 50 

Emerald 51 

Beryl 53 

Chrysoberyl 54 

Cymophane 56 

Alexandrite 56 

Zircon      ........  58 

Turquois 60 

Tourmaline 64 

Opal 69 

Pearl 71 

Chrysolite 78 

Garnet 80 

Topaz 84 

Apatite    ........  87 

Felspar 88 

Moonstone       .......  89 

Sunstone  (Avanturine  Felspar)           ...  90 

Amazon  Stone  (Green  Felspar)          .         .         .  91 

Labradorite 91 

Cyanite    .                  93 

Lapis  Lazuli     .......  94 

Hiddenite        .                  95 

Dichroite 97 

Idocrase 98 

Euclase 99 

Sphene 100 

Phenacite         .         .         .         .         .         .         .  101 

Epidote 101 

Axinite 102 

Diopside 103 

Fluor  Spar 104 


CONTENTS. 


Hypersthene    .......  i°5 

Quartz     ........  106 

Crystallized  Quartz  ......  109 

Amethyst          .......  no 

Yellow  Quartz          ......  in 

Cairngorm,  etc.         .         .         .         .         .         .  m 

Rose  Quartz     .......  113 

Avanturine       .         .         .         .         .         •         •  114 

Cat's-Eye          .......  114 

Crocidolite       .......  H5 

Heliotrope        .......  n6 

Chrysoprase      .         .         .         .         .         •         •  ny 

Prase        ........  "7 

Plasma     ........  n8 

Chalcedony      .......  118 

Agates     ........  i*9 

Onyx  or  Agate  Onyx         .         .         .         .         .  120 

Carnelian          .......  122 

Jasper      .......     .    .  123 

False  Lapis      .......  124 

Hematite          .......  124 

Obsidian           .......  125 

Malachite         .......  126 

Jet  .         .         .         .         .....  128 

Amber     ........  128 

Coral        ........  130 

Table  of  Hardness  and  Specific  Gravity    .        .  132 

Index       ........  135 


PREFACE. 

The  object  of  this  little  book  is  to 
convey  to  the  merchant,  the  workman, 
and  the  amateur,  in  a  condensed  and 
accurate  form,  information  concerning  the 
various  properties  of  precious  stones.  Be- 
sides drawing  freely  on  a  number  of  au- 
thorities, the  author  has  used  his  practical 
experience  to  indicate  such  tests  as  an 
amateur  can  readily  make.  Specific  grav- 
ity, hardness,  and  dichroism  are  tests 
which  are  easily  mastered,  and  a  thor- 
ough understanding  of  these  three  prop- 
erties will  assist  in  classifying  doubtful 
gems. 

Such  stones  have  been  dealt  with  prin- 
cipally as  are  used  in  commerce  for  jewelry 
and  ornamental  purposes. 

5 


6  PREFACE. 

The  attention  of  the  writer  has  often 
been  called  to  the  general  lack  of  knowl- 
edge among  the  jewelers  regarding  pre- 
cious stones  other  than  diamonds,  rubies, 
sapphires,  and  emeralds. 

As  there  are  so  many  other  beautiful 
and  rare  gems  which  nature  yields  to 
man,  and  which  are  worthy  of  the  jew- 
elers' art,  the  author  trusts  that  his  book 
will  awaken  a  new  interest  in  the  fascina- 
ting study  of  mineralogy  as  applied  to 
precious  stones,  and  that  at  some  future 
day  he  may  feel  encouraged  to  enlarge 
upon  this  treatise. 

M.  D.  ROTHSCHILD. 

41  and  43  MAIDEN  LANE, 
NEW  YORK. 


HAND-BOOK    OF    PRECIOUS 
STONES. 


WHAT  ARE  PRECIOUS  STONES? 

The  mineral  to  which  the  term  "  pre- 
cious stone "  is  applied,  must  be  adapt- 
able for  jewelry  or  ornamental  purposes 
and  must  possess  beauty,  hardness,  and 
rarity. 

The  beauty  of  a  precious  stone  or  gem 
consists  of  its  color  or  colorlessness,  bril- 
liancy or  softness  of  lustre,  and  transpa- 
rency. To  take  a  high  and  lasting  polish, 
a  mineral  must  be  hard, — and  many  stones 
that  would  otherwise  be  highly  valued  are 
low  in  the  estimate  of  worth  because  they 
do  not  possess  of  sufficient  hardness  to 
make  them  endure  the  wear  and  friction 
7 


8  PRECIOUS  STONES. 

to  which  a  precious  stone  is  subjected 
when  used  in  the  form  of  jewelry.  The 
rareness  of  precious  stones  has  a  decided 
effect  in  determining  their  values.  For 
instance,  the  crocidolite,  commercially 
known  as  tiger-eye,  was  sold  by  the  carat 
some  years  ago,  and  was  largely  used  in 
the  making  of  fine  jewelry.  To-day,  this 
material  is  so  plentiful  that  it  is  no  longer 
classed  among  the  higher  gems,  but  serves 
for  cameos  and  intaglios  like  chalcedony 
and  onyx. 

The  changes  of  fashion  have  much  to 
do  with  determining  the  market  value 
of  precious  stones.  Amethysts,  topazes, 
cat's-eyes,  aquamarines,  alexandrites,  and 
even  emeralds  and  opals  have  been 
eagerly  sought  for  at  times  and  then 
again  neglected  for  other  gems,  causing 
a  sensible  difference  in  the  value  of  these 
stones. 

There  are  all  degrees  of  precious 
stones,  from  the  valuable  diamond  and 


WHAT  ARE  PRECIOUS  STONES?       9 

corundums  to  the  humbler  quartz,  ame- 
thyst,  and  topaz. 

It  has  been  a  mooted  question  as  to  the 
proper  dividing  line  between  stones  that 
deserve  the  title  "  precious,"  and  those 
which  should  be  placed  in  a  so-called 
semi-precious  or  lower  category.  To  draw 
such  a  line  is  hardly  possible,  as  neither 
hardness,  rareness,  nor  value  would  be  a 
positive  test — some  of  the  hard  stones, 
like  zircon  and  almandines  being  less  valu- 
able than  the  softer  opal,  while  the  dia- 
mond, one  of  the  most  plentiful  of  precious 
stones,  is  at  the  same  time,  one  of  the  most 
valuable. 

Neither  can  price  be  taken  as  a  complete 
test,  because  fashion  makes  a  turquois,  an 
opal,  or  an  emerald  much  more  valuable  at 
one  time  than  at  another.  All  precious 
minerals  used  for  ornamental  purposes, 
from  the  diamond  to  quartz,  or  chalce- 
dony, may  properly  be  termed  precious 
stones. 


IO  PRECIOUS  STONES. 

PHYSICAL  CHARACTERS. 

CRYSTALLIZATION. 

Precious  stones  are  found  either  in 
crystallized  or  amorphous  conditions.  The 
forms  of  crystallization  are  : 

1  Isometric  or  Cubic  ;  having  the  axes  equal. 

2  Tetragonal  or  Pyramidal          \     having  only  the 

3  Hexagonal  or  Rhombohedral  f  lateral  axes  equal. 

4  Orthorhombic  or  Trimetric  .     .  \  hayi        h    axes 

5  Monochmc  or  Oblique    .     .     A  i L 

6  Tnchnic  or  Anorthic  .     .     .     .  ) 

Most  precious  stones  crystallize,  but  the 
specimens  that  have  the  crystallization 
clearly  defined  are  seldom  found.  The 
amorphous  condition  includes  the  turquois, 
opal,  and  obsidian,  which  minerals  are 
found  in  masses  or  veins  surrounded  by  a 
matrix. 

CLEAVAGE. 

Many  minerals  can  be  separated  readily 
in  one  direction  by  simply  making  a  small 
indentation  with  a  harder  mineral,  then 
introducing  the  blade  of  a  knife  into  the 
scratch  and  striking  it  a  sharp  blow, — this 
separates  the  crystal.  There  are  certain 


FRACTURE.  II 

planes  at  right  angles  where  the  crystal 
can  be  separated ;  this  property  is  called 
cleavage  and  the  planes,  cleavage  planes. 

In  some  minerals  cleavage  is  difficult  to 
produce,  while  in  others  such  as  mica  and 
rock-salt,  cleavage  is  highly  perfect  and 
the  number  of  separations  produced  is 
only  limited  by  the  thickness  of  the  blade 
used  in  separating  the  planes. 

The  property  of  cleavage  is  very  useful 
and  of  great  assistance  to  the  lapidary, 
as  it  enables  him  to  shape  a  diamond  or 
other  hard  stone  nearly  to  the  size  he 
desires,  and  at  the  same  time  to  save  the 
extra  material  cleaved  off,  which  can  be 
used  for  smaller  gems,  and  which  under 
other  conditions  would  have  to  be  ground 
away. 

FRACTURE. 

Fracture  surfaces  are  the  result  of  the 
breaking  of  a  crystal  otherwise  than  by 
cleaving,  and  in  a  different  direction  from 
the  cleavage  planes. 


12  PRECIOUS  STONES. 

When  the  form  of  fracture  is  composed 
of  concave  and  convex  surfaces  it  is  called 
conchoidal ;  when  free  from  inequalities 
it  is  known  as  even  or  smooth,  and  when 
covered  by  small  splinters,  splintery  or 
uneven. 

OPTICAL  PROPERTIES. 

REFRACTION. 

When  a  ray  of  light  passes  from  one 
medium  to  another,  or  from  the  air  to  a 
crystal  it  is  bent  or  refracted  ;  this  is  called 
single  refraction  and  takes  place  in  the 
diamond,  spinel,  and  garnet. 

Most  of  the  other  transparent  precious 
stones  possess  double  refraction — that  is, 
the  ray  of  light  enters  the  crystal  and 
divides  into  two  parts,  one  following  the 
ordinary  laws  of  refraction,  while  the  other 
part  or  extraordinary  ray  does  not  obey 
the  usual  law. 

There  are  precise  methods  for  measur- 
ing the  indices  of  refraction,  but  they  are 
not  applicable  to  polished  gem  stones. 


POLARIZATION  OF  LIGHT.  13 

POLARIZATION    OF    LIGHT. 

Polarization  is  a  peculiar  modification 
which,  under  certain  conditions,  a  ray  of 
light  undergoes.  This  property  is  easier 
to  observe  than  double  refraction. 

If  from  a  transparent  prism  of  tourma- 
line two  thin  plates  are  cut,  parallel  to 
its  axis,  they  will  transmit  light  when 
they  are  placed  above  each  other  with 
the  chief  axis  of  each  in  the  same 
direction. 

When  one  of  the  plates  is  turned  at 
right  angles  to  the  other,  no  light,  or  but 
very  little,  is  transmitted,  so  that  the 
plates  appear  black. 

In  passing  through  the  first  slip,  the 
rays  of  light  have  acquired  a  peculiar 
property,  which  renders  them  incapable 
of  being  transmitted  through  the  second, 
except  when  the  two  are  held  in  a  paral- 
lel position,  and  the  rays  are  then  said  to 
be  polarized. 

In  some  doubly  refracting  crystals  the 
two  oppositely  polarized  beams  are  of 


14  PRECIOUS  STONES. 

different  colors,  so  upon  double  refraction 
and  polarization  depends  the  property  of 
many  gems  which  is  called  pleiochroism. 

PLEIOCHROISM. 

The  dichroiscope  is  a  handy  little  opti- 
cal instrument,  that  will  readily  serve  to 
distinguish  the  diamond,  spinel,  or  garnet 
(all  singly  refracting  minerals)  from  the 
ruby,  beryl,  or  any  of  the  doubly  re- 
fracting stones.  This  instrument  consists 


FIG.  i. 


of  a  cleavage  rhombohedron  of  Iceland 
spar,  fastened  in  a  brass  tube  about  2J- 
inches  long,  and  f  of  an  inch  in  diameter. 
A  sliding  cap  at  one  end  has  a  perfora- 
tion -j-  of  an  inch  square,  and  at  the  other 
end  is  a  lens  which  will  show  a  distinct 


PLEIOCHROISM.  15 

image  of  the  square  opening  when  the 
cap  is  pulled  out  about  \  of  an  inch. 

The  pleiochroism  of  many  stones  can 
be  determined  at  a  glance  with  the 
dichroiscope. 

When  a  stone  is  examined  by  means  of 
the  dichroiscope,  it  will  show  two  images 
of  the  same  hue,  or  of  different  hues, 
these  square  images  (fig.  I,  A)  forming  a 
right  angle  and  being  more  distinct  when 
viewed  from  one  part  of  the  stone  than 
from  another. 

When  the  images  are  identical  in  color, 
the  specimen  may  be  a  diamond,  garnet, 
spinel,  or  glass.  Should  a  red  or  ruby 
spinel  approach  the  ruby  in  color,  a  quick 
and  satisfactory  test  can  be  made  with 
the  dichroiscope,  as  the  spinel  will  show 
two  images  of  one  color,  while  the  ruby 
will  show  one  image  of  aurora  red  and 
one  of  carmine  red. 

The  dichroiscope  is  inexpensive,  cost- 
ing but  a  few  dollars,  and  is  very  useful 
for  rapidly  deciding  the  species  of  many 


i6 


PRECIOUS  STONES. 


stones.  The  following  is  a  partial  list  of 
doubly  refracting  stones  and  their  twin 
colors. 


NAME   OF   STONE. 

TWIN  COLORS. 

Sapphire  (blue) 

Greenish  straw 

Blue 

Ruby  (red) 

Aurora  red 

Carmine  red 

Tourmaline  (red) 

Salmon 

Rose  pink 

"        (brownish  red) 

Umber  brown 

ColumbL     pink 

11        (brown) 

Orange  brown 

Greenisl       How 

"        (green) 

Pistachio  green 

Bluish  g 

"        (blue) 

Greenish  gray 

Indigo  \ 

Emerald  (green) 

Yellowish  green 

Bluish  £ 

Topaz  (sherry) 

Straw  yellow 

Rose  pii;-: 

Peridot  (pistachio) 

Brown  yellow 

Sea  gree 

Aquamarine  (sea  green) 

Straw  white 

Gray  blu 

Beryl  (pale  blue) 

Sea  green 

Azure  bl. 

Chrysoberyl  (yellow) 

Golden  brown 

Greenish     ^uow 

lolite  (lavender) 

Pale  buff 

[ndigo  blue 

Amethyst  (purple) 

Reddish  purple 

Bluish  purple 

COLORS. 

The   following   is  a  partial  list    of  the 

colors  of  precious  stones : 

Shades  of  White. — Quartz,  opal,  Chalce- 
dony. 

Shades  of  Gray. — Labrador,  sm^ky  to- 
paz, chalcedony,  zircon. 

Black. — Obsidian,  tourmaline,  jet. 


LUSTRE.  I/ 

Shades  of  Blue. — Lapis-lazuli,  amethyst, 
chalcedony,  spinel,  zircon,  sapphire, 
cyanite,  tourmaline,  turquois,  odonto- 
lite,  fluor  spar. 

Shades  of  Green. — Amazon  stone,  tur- 
quois, prase,  beryl,  bloodstone,  epidote, 
emerald,  malachite,  chrysoprase,  chrys- 
oL'  ••;,  idocras,  olivine,  garnet,  chryso- 
b  1. 

Sha^  ^  of  Yellow. — Opal,  amber,  topaz, 
1,  jasper. 

Shac*  bf  Red. — Garnet,  carnelian,  chalce- 
QO  y,  rose  quartz,  corundum,  tourma- 
line, spinel,  ruby. 

Shades  of  Brown. — Zircon,  garnet,  smoky 
topaz,  axinite,  jasper. 

Colo*  s. — Diamond,  sapphire,  spinel,  zir- 
coi  :topaz,  rock  crystal,  moonstone. 

LUSTRE. 

Well  polished  precious  stones  display  a 
decided  lustre,  which  assists  in  determin- 
ing their  species. 


1 8  PRECIOUS  STONES. 

The  following  is  a  list  of  some  precious 
stones  and  their  lustre  : 
Adamantine. — Diamond,  zircon. 
Resinous. — Garnet. 
Vitreous. — Emerald,  ruby,  spinel. 
Waxy. — Turquois. 
Pearly. — Moonstone,  opal. 
Silky.—  Crocidolite,  quartz  cat's-eye. 
Metallic. — Hematite. 
Greasy. — Olivine. 

Some  stones  vary  in  lustre,  from  vitreous 
to  pearly,  etc. 

STREAK. 

The  streak  of  a  mineral  is  the  color  of 
its  powder. 

This  powder  varies  in  color,  and  may  be 
white,  gray,  red,  etc.  It  is  obtained  by 
scratching  the  mineral  with  a  sharp  file,  or 
by  rubbing  the  mineral  on  the  back  of  an 
unglazed  porcelain  plate,  when  the  color 
of  the  powder  will  appear  on  the  plate. 

It  is  remarkable  that  the  streak  of  the 
diamond  is  gray  to  grayish-black,  while 
that  of  the  ruby  is  colorless  or  white. 


HARDNESS.  19 

HARDNESS. 

One  of  the  most  important  and  distin- 
guishing qualities  of  a  gem  stone  is  the 
property  of  enduring,  resisting  wear, — in 
short,  hardness.  To  test  the  hardness  of 
precious  stones  that  have  not  been  cut  or 
polished,  the  following  scale  of  ten  miner- 
als has  been  devised  by  Moh,  a  German 
mineralogist : 
No.  i.  Talc.  Very  soft;  is  easily  broken 

or  scratched  with  the  finger-nail. 
No.  2.  Rock-salt.      Soft ;    scratched  with 

difficulty  with  finger-nail ;  readily  cut 

with  a  knife. 
No.  3.  Calcite.     Low  degree  of  hardness ; 

not  to  be  scratched  with  finger-nail ; 

easily  scratched  with  a  knife. 
No.  4.  Fluor  spar.    Fairly  hard  ;  is  slightly 

scratched  by  a  knife,  but  easily  attacked 

with  a  file. 
No.  5.  Apatite.     Medium  hardness  ;  does 

not  scratch  glass,  or  only  faintly ;  does 

not  give  out  sparks  against  steel ;  easi- 
ly attacked  with  a  file. 


2O  PRECIOUS  STONES. 

No.  6.  Felspar.      Easily  scratches    glass ; 

is  attacked  by  a  file,  and  gives  some 

sparks  against  steel. 

No.  7.  Quartz.    Quite  hard  ;  is  only  slight- 
ly attacked  by  file  ;  gives  sparks  readily 

against  steel. 
No.  8.  Topaz.    Very  hard  ;  is  not  attacked 

by  a  file. 
No.  9.  Sapphire.     Hardest  of  all  minerals 

but   the   diamond ;    attacks   all   other 

minerals. 
No.  10.  Diamond.     Attacks  all  minerals ; 

is  not  attacked  by  any. 
To  find  the  hardness  of  a  stone,  begin 
to  test  with  the  softest  mineral,  so  that 
when  the  number  is  reached  which  will 
scratch  the  stone,  there  has  been  no  injury 
to  the  specimen  under  examination.  Half 
numbers  are  determined  by  the  ease  or 
difficulty  with  which  a  stone  is  scratched. 
For  example,  a  stone  which  will  resist  No. 
7  (quartz)  and  which  is  only  faintly  at- 
tacked by  No.  8  (topaz)  may  be  safely  put 
down  as  7.5,  while  a  stone  which  resisted 


SPECIFIC  GRAVITY.  21 

No.  7  and  yielded  easily  to  No.  8  is  to  be 
classed  as  7  in  hardness. 

These  tests  are  readily  applied  to  crys- 
tals or  unpolished  gems.  With  the  pol- 
ished stone  greater  care  must  be  observed, 
and  while  a  file  test  is  often  satisfactory, 
there  is  always  the  danger  of  striking  the 
cleavage  and  breaking  off  a  small  piece  of 
the  stone. 

SPECIFIC  GRAVITY. 

One  of  the  most  important  tests  which 
can  be  applied  to  a  polished  stone  is  that 
of  specific  gravity.  Many  stones,  like  the 
ruby  and  the  spinel,  the  blue  tourmaline 
and  the  sapphire,  etc.,  look  alike,  but  there 
is  a  sensible  difference  in  their  respective 
weights  that  a  specific-gravity  test  will 
readily  establish. 

The  weight  of  an  object  which  is  free  to 
seek  the  centre  of  gravitation  is  called  ab- 
solute weight,  while  the  weight  of  an  ob- 
ject compared  with  that  of  another  con- 


22  PRECIOUS  STONES. 

taining  the  same  volume  of  matter  is  called 
the  specific  weight. 

If  a  stone  weighing  16  carats  is  placed 
in  a  vessel  filled  to  the  brim  with  distilled 
water  and  the  stone  displaces  6  carats  of 
water,  the  specific  gravity  -of  the  stone 
would  be  1 6  -h  6,  or  2.66,  the  specific 
gravity  of  quartz. 

In  other  words,  the  stone  would  weigh 
1 6  carats  in  the  air  and  only  10  carats  in 
the  distilled  water,  showing  a  loss  of  6 
carats,  which  is  the  weight  of  the  volume  of 
water  equal  in  bulk  to  the  stone ; — or  ab- 
solute weight,  1 6  carats;  specific  weight, 
IO  carats;  loss,  6  carats ;  16  -=-  6  =  2.66, 
specific  gravity. 

There  are  several  methods  of  ascertain- 
ing the  specific  gravity  of  a  stone. 

First,  by  placing  it  in  liquids  of  known 
specific  gravity. 

Second,  by  weighing  the  stone  in  air 
and  then  in  distilled  water  or  alcohol,  and 
thus  learning  the  weight  of  an  equal  bulk 
of  water. 


SPECIFIC  GRAVITY.  2$ 

Third,  by  measuring  or  weighing  the 
water  which  the  stone  displaces  when 
immersed  in  a  small  vessel  of  known  ca- 
pacity. 

Fourth,  by  means  of  the  Nicholson 
hydrometer,  -a  simple  instrument  consist- 
ing of  a  hollow  glass  cylinder,  two  dishes, 
and  a  glass  vessel. 

As  the  jewelers'  balances  are  well 
adapted  for  the  ordinary  work  of  taking 
specific  gravity,  or  can  be  easily  adapted 
for  such  work,  the  second  method  will 
usually  be  the  more  practical  to  follow. 

The  author  has  had  very  satisfactory 
service  from  a  $30  balance,  and  any  well 
adjusted  balance  will  give  fair  results. 

The  following  accessories  are  necessary 
to  take  the  specific  gravity  of  a  stone : 

Distilled  water  about  60°  Fahr. 

A  very  fine  thread  of  platinum  wire 
with  which  to  suspend  the  stone  (fig  4  ). 

A  glass-beaker  for  the  water  (fig.  3,  C). 

A  bench  to  hold  the  beaker  over  the 
pan  (fig.  2). 


24 


PIG  3 


26  PRECIOUS  STONES. 

The  distilled  water  is  easily  obtainable 
from  any  druggist.  The  platinum  wire 
should  be  bent  to  hook  into  the  top  of 
the  balance  frame,  (fig.  3,  B)  and  for  ordi- 
nary small  stones  it  will  be  convenient 
to  twist  the  other  end  into  a  cork-screw 
shape  or  receptacle  (fig.  4,  A). 

The  beaker  can  be  a  small,  thin  glass 
cup  of  any  kind,  and  the  bench  is  easily 
produced  from  wood  (fig.  2)  or  of  metal 
with  three  supports  (fig.  3,  A). 

To  ascertain  the  specific  gravity,  attach 
the  platinum  wire  to  the  balance  frame,(fig. 
3,  B)  and  allow  the  lower  end  to  rest  in  the 
water ;  then  balance  this  carefully  by  add- 
ing weights  to  the  other  side  (fig.  3,  D) 
until  the  balance  is  exact. 

The  stone  to  be  weighed  in  water  is  a 
ruby,  and  weighs  two  carats  in  the  air. 

Clean  the  stone  carefully  with  water  to 
free  it  from  air  bubbles ;  then  place  it  in 
the  screw  of  the  wire  (fig.  4,  A)  and  weigh 
carefully.  If  the  stone  weighs  ij  carats 
it  will  have  displaced  %  ct.  of  water :  or, 


WEIGHT.  27 

weight  in  air,  2  carats  ;  weight  in  water,  i£ 
carats  ;  loss,  J  carat ;  2  -f-  J-  —  4,  which 
will  be  the  specific  gravity  of  the  ruby. 

The  Jolly  spiral  balance  can  also  be 
used  for  taking  specific  gravity,  but  it  is 
not  so  practical  or  accurate  for  small 
stones  as  for  the  larger  ones. 

WEIGHT. 

The  valuable  precious  stones  are  bought 
and  sold  by  the  carat.  This  weight  is 
equal  to  about  3.17  grains  or  about  .205 
milligrams. 

The  carat  is  divided  into  fractions  of  \, 
i>  i>  iV'  A'  A'  and  also  arbitrarily  into 
four  grains ;  that  is,  each  quarter  of  a  carat 
is  counted  one  grain,  thus  forming  the 
basis  for  the  calculation  of  pearls. 

In  commerce,  a  carat  diamond  is  some- 
times called  a  four-grain  stone,  and  a  carat- 
and-a-half  stone  is  six  grains,  etc.,  etc. 

The  weight  of  the  carat  being  arbitrary, 
it  varies  in  different  countries,  some  being 
heavier  and  others  lighter  than  .205  milli- 
grams. 


28  PRECIOUS  STONES. 

The  writer  wrote  to  three  prominent 
balance-makers  in  the  United  States  some 
months  ago  for  their  carat  standards  and 
was  surprised  to  find  that  they  all  differed. 
This  will  account  for  discrepancies  in 
weight  resulting  between  the  balances  of 
different  makers.  Of  late  there  has  been 
a  decided  movement  in  Europe,  headed 
by  the  French  Chambre  Syndicale  of  jew- 
elers, in  favor  of  the  unification  of  the 
carat,  so  that  the  weight  of  a  French  or 
Dutch  carat  will  equal  that  of  an  English, 
American,  or  any  other  carat.  This  re- 
form will  probably  be  accompanied  by 
the  adoption  of  the  decimal  system  of 
dividing  the  carat,  and  the  discarding  of 
the  complicated  fractional  system. 

After  having  tried  the  decimal  weights 
for  many  months,  the  author  can  testify 
to  a  decided  gain  in  time  and  accuracy 
from  their  use. 

FUSIBILITY. 
The  blow-pipe  or  dry  test   for  minerals 


FUSIBILITY.  29 

is  convenient  to  apply  to  small  bits  or 
splinters  of  a  stone. 

The  mineral  is  either  held  by  a  pair  of 
platina-pointed  forceps,  or  powdered  and 
placed  on  a  metal  plate  or  in  a  glass  tube. 

Before  the  blow-pipe,  some  minerals 
change  color,  but  do  not  melt,  while 
others  retain  their  color,  or  swell  up,  or 
break  into  small  particles,  or  melt  into 
colorless  or  colored  glasses. 

The  following  is  the  scale  of  minerals 
used  to  test  the  different  degrees  of  fusi- 
bility : 

1.  Gray   Antimony.       Fusible   in    coarse 

splinters  in  summit   of   candle   flame 
without  the  blow-pipe. 

2.  Natrolite.     Fusible  in  fine  splinters  in 
the  summit  of  a  candle  flame  without 
the  blow-pipe. 

3.  Almandite.      Does  not  fuse  in  candle 

flame  ;    fuses  easily  before   the   blow- 
pipe in  obtuse  pieces. 

4.  Green  Actinolite.     Fusible  before  the 

blow-pipe  in  coarse  splinters. 


30  PRECIOUS  STONES. 

5.  Orthoclase.     Fusible  before  the  blow, 
pipe  in  fine  splinters. 

6.  Bronzite.      Before   the    blow-pipe    be- 
comes   rounded    only    on    the   sharp 
edges. 

MAGNETISM. 

There  are  but  few  precious  stones  that 
possess  the  power  to  act  on  the  magnetic 
needle ;  among  them  are  the  chrysolite, 
cinnamon  stone,  almandine,  pyrope,  and 
garnet. 

TRANSPARENCY. 

Precious  stones  are,  on  the  basis  of  their 
relative  transparency,  divided  into  four 
classes,  as  follows :  Transparent,  or  ad- 
mitting light  freely  and  clearly ;  defining 
objects  when  used  as  a  lens.  Semi-trans- 
parent, admitting  light,  but  only  partially 
defining  objects.  Translucent,  admitting 
light  faintly.  Opaque,  not  admitting  light. 

The  more  valuable  precious  stones,  ex- 
cepting opals  and  turquoises,  are  generally 
transparent. 


PHOSPHORESCENCE. — ELECTRICIT  Y.    31 
PHOSPHORESCENCE. 

Some  precious  stones  display  a  distinct 
phosphorescence  after  exposure  to  the 
sunlight,  and  also  upon  the  application  of 
artificial  heat,  and  through  mechanical  and 
electrical  means. 

Many  diamonds,  when  taken  to  a  dark 
room,  appear  quite  luminous  ;  this  is  also 
true  of  topaz,  fluor  spar,  and  other  miner- 
als. 

ELECTRICITY. 

Minerals  acquire  electricity  through 
friction  or  heating,  and  in  this  state  read- 
ily attract  or  repel  small  bits  of  paper  and 
other  light  substances. 

All  minerals  are  electric,  some  display- 
ing positive  and  others  negative  electricity. 

The  electric  test  of  a  precious  stone  re- 
fers to  the  length  of  time  that  a  stone  will 
retain  electricity  after  friction  or  heating. 

Some  stones  lose  this  quality  in  a  few 
minutes,  while  others  retain  it  a  long  time. 


32  PRECIOUS  STONES. 

The  tourmaline  is  noted  for  its  electrical 
properties,  while  the  Brazilian  topaz  ren- 
dered electric  by  heating  or  rubbing  has 
been  known  to  affect  the  electric  needle 
after  32  hours. 

CUTTING  AND  POLISHING. 

Although  a  finely  developed  diamond, 
ruby,  or  other  crystal  is  sometimes  found 
and  used  for  jewelry,  the  beauty  of  a 
precious  stone  generally  remains  hidden 
within  a  rough  and  unsightly  exterior 
until  the  lapidary's  art  reveals  the  gem. 

According  to  well  known  rules,  there  is 
one  kind  of  cutting  or  faceting  for  the 
diamond  or  colorless  gems  and  another  for 
colored  gems. 

The  brilliant  cut,  figs.  5  and  6,  consists  of 
an  arrangement  of  fifty-six  facets,  exclusive 
of  the  table  and  culet.  This  cut  is  some- 
times improved  by  the  addition  of  eight 
star  facets  around  the  culet,  which  brings 
the  number  of  facets  up  to  sixty-four. 


CUTTING  AND  POLISHING.  33 

The  following  are  the  proportions  of  a 
well  cut  diamond  or  colorless  gem  : 
\  above  the  girdle,  fig.  6,  A. 
f  below    "         "         "     6,  B. 
The  table  f  of  the  breadth  of  the  stone, 

fig.  6,  C. 
The  culet  |  of  the  size  of  the  table,  fig. 

6,D. 


IJQ.5 


These  proportions  do  not  refer  to  colored 
gems,  which  are  cut  thick  or  shallow  to 
deepen  or  diminish  the  color  of  the  stone. 
The  step  cut,  fig.  7,  now  principally  used 
for  emeralds,  can  be  advantageously  used 
for  other  colored  stones. 

The  crowned  rose  cut,  fig.  8,  is  applied 
to  small  diamonds,  and  occasionally  to  col- 


34 


PRECIOUS  STONES. 


ored  gems.  This  cut  consists  of  twenty- 
four  facets,  and  a  well  proportioned  rose 
is  one  half  of  its  diameter  in  thickness. 


A/IVKA 


FIG,  9 


TIG,  10 


To  the  smaller  and  more  common  roses 
only  twelve  facets  are  given. 

Besides  the  above-mentioned  forms, 
there  are  the : 

Huitpan,  or  single  cut. 

16  facet     "  double  " 

24     "         "  single  brilliant. 

Cabochon  "  carbuncle. 

Star  cut,  fig.  9. 

Degree  or  rose  cut,  fig.  10. 


DIAMOND.  35 

The  last  two  beautiful  forms  of  cutting 
are  frequently  given  to  fine  paste  or  imita- 
tion diamonds. 

Of  late  years  nearly  all  gems  have  been 
cut  quite  round,  and  In  many  instances 
with  a  sacrifice  of  size  and  brilliancy. 

DIAMOND. 

The  diamond  is  one  of  the  most  precious 
minerals,  and  yet  it  consists  of  pure 
carbon,  the  most  common  substance  that 
is  known,  a  substance  that  is  present  in  all 
animal  and  vegetable  bodies  and  in  the 
larger  number  of  minerals.  When  carbon 
is  crystallized  the  result  is  the  diamond, 
which  is  always  found  in  detached  crystals, 
either  octahedrons  or  rhombic  dodecahe- 
drons, the  planes  of  the  angles  being  often 
convex  or  rounded, — this  curving  crystal 
being  peculiar  to  the  diamond. 

The  cleavage  is  perfect,  and,  parallel  to 
the  faces  of  the  octahedron,  the  fracture  is 
conchoidal  or  curved.  The  diamond  is 
not  acted  upon  by  acids  or  alkalies,  is  in- 


36  PRECIOUS  STONES. 

fusible  but  combustible,  and  burns  under 
heat  of  a  very  high  temperature.  Dia- 
mond powder  burns  readily,  but  larger 
pieces  are  not  affected  by  the  blow-pipe. 

The  diamond  is  a  non-conductor  of 
electricity,  but  acquires  positive  electricity 
when  rubbed,  and  retains  it  for  half  an 
hour.  After  being  exposed  to  the  solar 
rays,  the  diamond  presents  a  distinct 
phosphorescence  in  the  dark.  It  possesses 
single  refraction,  but  belongs  to  those 
bodies  which  reflect  light  most  strongly, 
and  its  magnifying  power  is  much  greater 
than  that  of  glass  ;  it  does  not  polarize 
light ;  its  lustre  is  adamantine,  and  specific 
gravity  3.5  to  3.6.  The  diamond  is  the 
hardest  of  all  known  minerals,  ranking 
No.  10  in  Moh's  scale  of  hardness. 

White,  and  the  different  shades  from 
very  light  yellow  to  dark  yellow  or  ca- 
nary, comprise,  according  to  the  popular 
idea,  the  colors  of  the  diamond.  Yet  the 
diamond  is  found  in  green,  red,  blue, 
brown,  olive,  orange,  and  black,  and  also 


DIAMOND  37 

in  the  various  shadings  of  these  colors 
and  in  opalescent  tints. 

As  the  limpid  or  white  diamond  sur- 
passes all  other  white  stones  in  the  power 
of  its  lustre  and  the  magnificence  of  its 
fire,  so  do  the  colored  diamonds  outrank 
the  emerald,  ruby,  sapphire,  and  other 
gems  of  like  colors. 

Colored  diamonds,  excepting  light  yel- 
low and  brown,  are  rare,  and  hence  are 
the  most  valuable  of  precious  stones. 
The  limpid  or  perfectly  white  and  the 
white  with  a  bluish  tint  are  the  most 
sought  after,  while  fine  deep  golden  yel- 
low or  canaries  and  pronounced  fancy 
colors  always  find  a  ready  market. 

Diamonds  come  principally  from  the 
mines  in  South  Africa ;  some  are  found 
in  Brazil  and  India,  and  fewer  in  Sumatra, 
Borneo,  the  Ural  Mountains,  and  Aus- 
tralia. Crystals  have  also  been  found  in 
the  United  States. 

The  amorphous  or  carbon  diamond  is 
found  only  in  Brazil.  The  pebbles  or 


38  PRECIOUS  STONES. 

masses  are  opaque,  steel-gray  to  black  in 
color,  and  sometimes  weigh  1,000  carats. 

This  carbonate  is  principally  used  to 
point  rock-drills  and  for  other  engineering 
purposes.  The  coarse  variety  of  crys- 
tallized diamonds  is  called  bort,  and  as 
this  is  unfitted  for  gem  purposes  because 
of  imperfections,  it  is  ground  into  powder 
and  used  for  cutting  and  drilling  precious 
stones. 

White  sapphires,  white  zircons,  white 
topaz,  and  rock-crystal  sometimes  pass 
for  diamonds.  The  first  two  are  heavier, 
the  topaz  lacks  brilliancy,  and  the  crystal 
is  lighter  than  the  diamond. 

It  is  also  the  case  that  these  four  stones, 
especially  the  crystal,  are  easily  scratched 
by  a  diamond. 

The  best  style  of  cutting  for  a  diamond 
is  the  brilliant,  of  66  facets,  including  the 
table  and  culet.  The  proper  proportions 
of  a  well  cut  brilliant  is  \  for  the  crown 
and  f  for  the  collet.  The  table  and  culet 
must  also  be  in  proportion  to  the  size  of 
the  stone. 


CORUNDUM.  39 

CORUNDUM. 

This  many-colored  mineral,  composed 
of  nearly  pure  alumina,  produces  gems 
which  in  some  cases  are  more  valuable 
even  than  diamonds.  The  ruby,  sapphire, 
Oriental  emerald,  Oriental  topaz,  Oriental 
amethyst,  Oriental  aquamarine,  Oriental 
chrysolite,  Oriental  hyacinth,  star  ruby, 
star  sapphire,  star  topaz,  and  ruby  and 
sapphire  cat's-eyes  are  all  corundums  of 
different  colors.  The  ruby  is  a  red  sap- 
phire, and  the  Oriental  topaz  a  yellow 
sapphire,  while  the  Oriental  emerald  is  a 
green  sapphire,  etc.,  etc. 

In  hardness  corundum  ranks  next  to 
the  diamond,  ranking  No.  9  in  Moh's  scale. 

The  specific  gravity  is  3.9  to  4.1,  the 
crystallization  rhombohedral,  and  cleavage 
basal,  the  crystals  breaking  across  the 
prism  with  nearly  a  flat  surface. 

In  lustre,  the  corundum  is  vitreous,  its 
refraction  double  but  not  to  a  high  de- 
gree, and  it  is  susceptible  of  electricity 
by  friction,  which  the  polished  specimens 
especially  retain  for  a  considerable  time. 


4O  PRECIOUS  STONES. 

Corundum  is  unaffected  by  chemicals, 
and  is  infusible  alone,  but  in  combination 
with  a  flux  it  melts  with  difficulty  into  a 
clear  glass. 

The  chemical  composition  of  precious 
corundum  is : 

Alumina,  98.5 

Oxide  of  iron,       i.o 
Lime,  0.5 


Thus  it  will  be  seen  that  corundum  is 
composed  almost  wholly  of  alumina, — 
one  of  the  constituents  of  common  clay, 
which,  when  colored  by  traces  of  metallic 
oxides,  chrome,  etc.,  produces  a  greater 
variety  of  precious  stones  of  a  high  rank 
than  any  other  mineral. 

THE  RUBY. 

The  red  sapphire  or  ruby  is  the  most 
valuable  of  the  corundum  family,  and 
when  found  of  a  good  color,  pure  and 
brilliant,  and  in  sizes  of  one  carat  and 
larger,  it  is  much  more  valuable  than  a 
fine  diamond  of  the  same  size. 


THE  RUBY.  41 

Fine  rubies  larger  than  i£  to  2  carats 
are  very  rare,  and  when  a  fine  stone  from 
3  to  5  carats  is  offered  for  sale,  the  price 
mounts  into  the  thousands. 

The  color  varies  from  the  lightest  rose 
tint  to  the  deepest  carmine  ;  that  color, 
however,  which  has  the  greatest  value  is 
known  in  commerce  as  pigeon's  blood,  and 
is  the  color  of  arterial  blood,  or  of  the  very 
centre  of  the  red  ray  in  the  solar  spectrum. 

The  imperfections  in  rubies,  as  in  all 
corundums,  consist  largely  of  clouds, 
milky  spots,  and  cracks.  A  perfect  ruby 
is  rarely  met  with,  and  a  stone  possessing 
brilliancy  and  the  true  color,  even  if 
slightly  defective,  is  considered  more 
valuable  than  an  absolutely  perfect  ruby 
of  an  inferior  color. 

Rubies  are  found  in  Siam,  Ceylon,  Bur- 
mah,  Brazil,  Hindustan,  Borneo,  Sumatra, 
Australia,  France,  and  Germany. 

Where  rubies  and  sapphires  are  met 
with  it  is  said  that  gold  is  almost  sure  to 
be  present. 


42  PRECIOUS  STONES. 

Chemists  have  succeeded  in  producing 
minute  crystals  of  rubies  and  sapphires 
which,  under  the  microscope,  presented 
the  true  crystallization  of  corundums,  and 
upon  being  tested  proved  to  be  of  the 
same  hardness  as  rubies  and  sapphires ; 
but  these  specimens  were  small,  and  cost 
very  much  more  to  produce  than  their 
commercial  value. 

Ruby  spinels,  garnets,  hyacinths,  red 
quartz,  burnt  Brazilian  or  rose  topaz,  and 
red  tourmaline  are  sometimes  passed  off 
for  the  ruby. 

The  true  ruby  will  scratch  all  of  these 
stones  readily,  the  spinel  is  lighter  in 
specific  gravity,  and  has  generally  a  slight 
tinge  of  yellow,  even  in  the  most  pro- 
nounced red  specimens. 

The  ruby  will  turn  green  under  the 
flames  of  a  blow-pipe,  but  when  cooled 
off,  resumes  its  original  color. 

The  garnet  and  topaz  are  easily  scratched 
by  the  ruby,  the  hyacinth  is  heavier,  and 
quartz  and  tourmaline  lighter  than  the 


SAPPHIRE.  43 

ruby.  Some  so-called  reconstructed  ru- 
bies, recently  offered  for  sale,  are  of  a 
very  fine  color,  and  closely  resemble  the 
Oriental  gems. 

The  hardness  and  specific  gravity  are 
the  same,  but  they  differ  in  one  very  im- 
portant point,  namely:  they  lack  the 
brilliancy  of  the  true  ruby.  In  addition 
to  this  lack  of  fire,  a  microscopical  test 
discloses  formations  which  will  distinguish 
the  manufactured  from  the  natural  stone. 

SAPPHIRE. 

The  blue  corundum,  ranging  in  color 
from  the  lightest  blue  to  deep  blue  and 
black,  is  the  same  stone  as  the  ruby,  the 
only  difference  being  in  the  color. 

The  choicest  color  is  the  soft  velvety 
blue,  approaching  the  corn-flower  in  shade 
and  exhibiting  that  color  vividly  by  arti- 
ficial as  well  as  by  natural  light. 

The  deeper-colored  stones  are  known  as 
male,  and  the  light-colored  ones  as  female 
sapphires. 


44  PRECIOUS  STONES. 

Although  choice  sapphires  are  rare,  a 
much  greater  quantity  of  good  and  large 
stones  are  to  be  had  than  of  rubies,  and 
therefore  the  price  of  a  large  sapphire  does 
not  advance  in  the  same  proportion  as  the 
price  of  a  large  ruby. 

FANCY  SAPPHIRES. 

The  Oriental  emerald  or  green  sapphire 
does  not  approach  the  beryl  or  true 
emerald  in  depth  of  color,  but  because  of 
its  superior  hardness  and  brilliancy,  added 
to  its  extreme  rarity,  it  is  the  most  valua- 
ble of  green  gems.  The  Oriental  amethyst 
or  purple  sapphire  sometimes  reflects  a 
red  color  by  artificial  light,  and  is  valued 
highly  as  a  gem  stone  ;  the  common 
amethyst  is  softer,  less  brilliant,  and  loses 
by  artificial  light. 

The  various  other  colored  sapphires, 
such  as  yellow  or  Oriental  topaz,  light 
green  or  Oriental  aquamarine,  greenish- 
yellow  or  Oriental  chrysolite,  and  aurora- 
red  or  Oriental  hyacinth,  are  all  valuable 


STAR  SAPPHIRES.  45 

as  gem  stones  when  they  are  pure,  well 
cut,  and  have  pronounced  colors — in  fact, 
the  name  Oriental  is  given  to  distinguish 
the  corundums  from  the  less  valuable 
minerals  of  the  same  colors  which  they 
resemble,  but  which  they  greatly  surpass 
in  beauty  and  value  because  of  their  bril- 
liancy and  superior  hardness. 

STAR  SAPPHIRES. 

Asterias  or  star  stones  are  corundums 
of  three  different  colors ;  the  star  sapphire 
proper  is  a  grayish  blue,  the  star  ruby  red, 
and  the  star  topaz  yellow. 

These  stones  are  usually  cut  cabochon 
or  convex,  and  display  under  the  rays  of 
the  sun,  or  when  exposed  to  one  candle  or 
other  artificial  light,  a  beautiful  star  with 
six  points. 

This  star  is  produced  by  foreign  sub- 
stances in  the  corundum,  and  the  lapidary 
brings  about  the  regular  effect  by  cutting 
a  pointed  carbuncle  so  that  the  centre  of 
the  star  begins  at  the  apex,  and  the  six 


46  PRECIOUS  STONES. 

bright  stripes  radiate  to  the  base  of  the 
stone. 

The  bright  lines  of  the  star  following 
the  light  move  over  the  surface  of  the 
stone  and  produce  a  remarkable  effect. 
These  stones  are  amongst  the  most  won- 
derful of  mineral  productions,  and  good 
specimens  are  very  valuable. 

The  corundum  cat's-eye,  called  Oriental 
girasol  or  sunstone,  has  a  bluish,  reddish, 
or  yellowish  reflection  of  light  of  a  lighter 
shade  than  the  stone  itself,  and  which 
moves  on  the  convex  surface  of  the  stone 
like  the  lines  of  a  star  stone. 

SPINEL. 

It  is  only  during  the  past  century  that 
mineralogists  make  a  distinction  between 
the  minerals  spinel  and  corundum. 

The  composition  of  the  spinel  was  dis- 
covered towards  the  end  of  the  last  cen- 
tury, and  was  found  to  be  about  seventy 
per  cent,  alumina,  twenty-five  per  cent, 
magnesia,  and  small  parts  of  oxide  of 
chrome,  silica,  and  protoxide  of  iron. 


SPINEL.  47 

Up  to  that  time,  red  spinels  had  always 
been  confounded  with  rubies,  and  many 
celebrated  so-called  rubies  have  been 
shown  to  be  spinels  by  modern  mineralo- 
gists. 

This  beautiful  mineral  is  found  in  many 
colors,  from  pink  to  rose-red,  carmine, 
cochineal,  blood-red,  hyacinth,  pale  to 
dark  blue,  violet  and  indigo  blue,  grass- 
green  to  blackish  green,  and  sometimes 
colorless.  There  is  also  a  black  variety 
called  pleonaste  or  ceylonite.  Spinels  crys- 
tallize in  octahedrons  and  their  modifica- 
tions, the  fracture  is  conchoidal,  specific 
gravity  3.5  to  3.6,  and  hardness  No.  8  in 
Moh's  scale  ;  only  the  diamond,  corundum 
and  chrysoberyl  will  scratch  the  spinel. 

Its  refraction  is  single,  the  lustre  highly 
vitreous,  and  it  does  not  easily  acquire 
electricity. 

Acids  do  not  attack  the  spinel,  nor  has 
the  blow-pipe  any  effect  on  this  mineral, 
except  to  change  the  red  to  a  brownish 
or  colorless  state,  but  the  original  color 
returns  when  the  stone  cools. 


48  PRECIOUS  STONES. 

Flawed  or  imperfect  stones  are  liable  to 
crack  or  split  if  heated  too  much.  With 
borax  or  salt  of  phosphorus  the  spinel 
melts  into  a  colorless  or  green-tinted 
glass. 

Spinels  are  found  in  clay  and  in  the 
sands  of  rivers,  in  East  India,  Hindustan, 
the  province  of  Mysore,  Farther  India, 
Pegu,  Ceylon,  North  America,  Sweden, 
Bohemia,  and  Australia. 

The  red  spinel,  and  especially  those  tints 
which  approach  the  red  corundum  or  true 
ruby  in  color,  are  the  most  valuable,  and 
are  known  as  ruby  spinels. 

Very  fine  specimens  of  ruby  spinels  of 
one  carat  and  larger  are  quite  rare  and 
command  good  prices. 

Rose-colored  spinels  are  known  as  balas- 
rubies,  pale-blue  spinels  as  sapphirines, 
and  the  hyacinth-red,  yellowish-red,  and 
orange-yellow  spinels  are  called  rubicelles. 

All  these  different-colored  spinels,  if 
pure  and  of  great  brilliancy,  are  valuable 
as  gem  stones,  being  only  surpassed  in 


SPINEL.  49 

hardness  and  brilliancy  by  the  diamond 
and  corundums. 

The  white  spinel,  which  is  seldom  found, 
is  sometimes  confounded  with  the  dia- 
mond, having  the  same  specific  gravity 
and  single  refraction,  but  as  it  lacks  the 
fire  and  is  easily  scratched  by  the  diamond, 
the  danger  of  mistaking  one  for  the  other 
is  slight.  Burnt  amethyst,  which  often 
resembles  the  spinel,  is  lighter  and  softer, 
while  burnt  topaz,  although  it  is  identical 
with  the  spinel  in  hardness,  is  somewhat 
lighter  and  possesses  remarkable  electric 
powers,  becoming  electric  by  either  rub- 
bing, heating,  or  pressure,  and  retaining 
electricity  for  upwards  of  twenty-four 
hours. 

The  zircon  is  easily  distinguished  from 
the  spinel  because  of  its  much  greater 
specific  gravity.  It  is  also  doubly  refrac- 
tive and  softer. 

Garnets  are  softer,  lack  the  play  of  color 
and  brilliancy,  and  fuse  easily  into  a  light- 
brown  or  black  glass. 


50  PRECIOUS  STONES. 

BERYL. 

The  beryl  is  a  mineral  belonging  to  the 
primitive  formation,  and  is  found  in  quartz 
veins  and  granite. 

It  crystallizes  in  six-sided  prisms  and  is 
composed  largely  of  silica,  the  third  most 
common  of  earth's  productions.  The 
beryl  is  7.5  to  8.  in  hardness,  scratching 
quartz,  but  is  scratched  by  topaz. 

The  specific  gravity  is  2.67  to  2.73, 
making  it  one  of  the  light  minerals. 
Its  lustre  is  vitreous  and  refraction  double 
to  a  slight  degree ;  its  cleavage  is  imper- 
fectly basal,  and  it  becomes  electric  by 
rubbing. 

Acids  do  not  attack  the  beryl,  but  it 
melts  with  borax  and  is  soluble  in  salts  of 
phosphorus. 

This  stone  is  found  in  various  colors, 
grass-green,  pale-green,  light-blue,  green- 
ish-blue, greenish-yellow,  yellow,  and  some- 
times pink. 

The  most  important  of  these  colors  is 
the  grass-green,  which  forms  a  separate 


EMERALD.  5 1 

division  of  the  beryl  family,  and  is  known 
as  the  emerald. 

EMERALD. 

The  emerald  or  green  beryl  is  one  of 
the  most  highly  prized  of  the  gem  stones. 
Its  magnificent  color  has  rightly  been 
compared  to  the  color  of  the  fresh  grass 
in  spring,  and  in  brilliancy  this  stone  far 
exceeds  all  other  green  gems,  excepting 
only  the  very  rare  green  corundrum  or 
green  sapphire. 

The  emerald  is  said  to  be  very  soft 
when  first  withdrawn  from  the  mine,  but 
it  hardens  by  exposure  to  the  air. 

A  perfect  emerald  of  fair  size  is  a  rarity, 
so  that  the  saying  "  an  emerald  without 
a  flaw  "  has  passed  into  a  proverb. 

This  stone  is  so  light,  compared  to  a 
diamond  or  sapphire,  that  a  carat  emerald 
will  be  very  much  larger  than  either  of 
the  above  stones. 

The  emerald  is  composed  of : 


52  PRECIOUS  STONES. 

Silica 68.50 

Alumina       .     .     .     .15.75 

Glucina 12.50 

Peroxide  of  iron    .     .     i. 

Lime 0.25 

Oxide  of  chrome   .     .     0.30 
And  traces  of  magnesia,  of  lime,  and  of  soda. 

The  vivid  green  color  of  the  emerald  is 
supposed  to  come  from  the  oxide  of 
chrome,  as  the  other  beryls  do  not  con- 
tain  chrome. 

Emeralds  are  found  in  New  Granada, 
near  Bogota,  Egypt,  East  India,  Burmah, 
Ural  in  Europe ;  Salzburg,  Austria ;  Mt. 
Remarkable,  South  Australia  ;  and  North 
America.  Some  of  the  finest  come  from 
the  mines  of  Muza,  near  Bogota,  and  the 
best  stones  are  called  Peruvian  emeralds. 
During  the  conquest  of  Peru  by  the  Span- 
iards, many  very  fine  emeralds  were  de- 
stroyed by  the  invaders,  who  tested  them 
by  grinding  and  pounding,  and  concluded 
that  the  emeralds  were  worthless,  because 
they  were  not  as  hard  as  the  diamonds  or 
sapphires. 


BERYL.  53 

In  1587,  Joseph  D'Acosta  returned  to 
Spain  with  two  cases  of  emeralds,  each 
case  weighing  one  hundred  pounds. 

Green  tourmaline  sometimes  passes  for 
the  emerald,  but  it  is  somewhat  softer 
and  considerably  heavier. 

Olivines  or  chrysolites,  if  of  a  fine  green 
color,  sometimes  resemble  the  emerald, 
but  they  are  much  heavier  than  the  em- 
erald and  have  a  fatty  lustre.  Green  spi- 
nels are  heavier  and  harder  than  emeralds. 

BERYL. 

The  second  and  less  valuable  division 
of  the  beryl  family  comprises  the  follow- 
ing colors : 

Clear  light  sky-blue,  called  by  lapidaries 
aquamarine  ;  very  light  greenish-blue, 
known  as  Siberian  aquamarine ;  and  a 
greenish-yellow  variety,  called  aquama- 
rine chrysolite. 

These  three  kinds  are  usually  very  bril- 
liant, and  especially  so  by  artificial  light, 
in  which  respect  the  beryl  is  superior  to 


54  PRECIOUS  STONES. 

many  of  the  more  valuable  gem  stones. 
Beryls  of  very  large  size  have  been  found 
in  New  Hampshire,  one  of  which  has  been 
estimated  to  weigh  over  two  tons.  While 
the  large  specimens  are  worthless  for  gem 
stones,  some  very  handsome  aquamarines 
and  golden-yellow  beryls  have  been  found 
during  the  past  few  years  in  New  Hamp- 
shire and  Connecticut.  These  stones, 
when  cut,  compare  favorably  with  the 
best  of  their  kind. 

CHRYSOBERYL. 

The  name  chrysoberyl  is  derived  from 
two  Greek  words  signifying  golden-beryl. 
This  name  is  well  suited  to  the  golden- 
yellow  variety,  but  the  chrysoberyl  also 
includes  many  other  colors  :  such  as  green, 
greenish-yellow,  brownish-yellow,  white, 
and  dark-brown  to  black. 

Three  varieties  of  chrysoberyls  are 
known  as  cat's-eyes,  cymophanes,  and 
alexandrites. 

The    chrysoberyl    crystallizes    in    the 


CHRYSOBERYL.  55 

trimetric  or  rhombic  system  ;  the  cleav- 
age is  imperfect ;  fracture  conchoidal ; 
hardness,  8.5,  being  the  third  hardest 
stone  ;  specific  gravity,  3.65  to  3.8  ;  and 
lustre  vitreous  to  greasy. 

The  composition  of  the  chrysoberyl  is: 
alumina,  80.2;  glucina,  19.8;  with  traces 
of  protoxide  of  iron  and  oxides  of  lead 
and  copper.  The  chrysoberyl  is  doubly 
refractive  to  a  high  degree,  acquires  posi- 
tive electricity  lasting  several  hours,  is 
infusible  alone,  but  melts  with  borax  or 
salts  of  phosphorus  to  a  clear  glass, 
though  with  difficulty. 

The  chrysoberyl  is  unaffected  by  acids, 
but  with  a  solution  of  cobalt  nitrate  the 
powdered  mineral  becomes  blue. 

Transparent  greenish-yellow  chryso- 
beryls  are  sometimes  called  Oriental 
chrysolites.  These,  and  the  brownish- 
yellow  stones  are  the  gems  most  used  in 
jewelry. 

The  chrysoberyl  cat's-eye,  or  Ceylon 
cat's-eye,  is  found  in  various  shadings  of 


56  PRECIOUS  STONES. 

yellow,  brown,  and  green,  and  sometimes 
nearly  black.  These  stones  are  translu- 
cent to  opaque,  and  have  a  bright  band 
of  light  running  through  the  centre. 
This  band  is  nearly  always  white,  and  in 
fine  specimens  is  sharply  defined,  not  too 
wide,  and  is  in  the  centre  of  the  stone. 

The  cat's-eye  chrysoberyls  are  always 
cut  convex  or  cabochon  shape,  and  as  the 
stone  is  moved  from  side  to  side  the  band 
of  light  moves  over  its  surface. 

CYMOPHANE. 

The  cymophane,  or  floating  light,  as 
the  name  denotes,  is  a  chrysoberyl  with  a 
bright  spot  of  light  which  seems  to  float 
over  the  surface  as  the  stone  is  moved. 
The  cymophane  is  also  cut  cabochon. 

ALEXANDRITE. 

On  the  day  that  the  Emperor  Alexan- 
der of  Russia  attained  his  majority  the 
Ural  chrysoberyl,  of  a  dark-green  color, 


ALEXANDRITE.  57 

was  found  in  the  emerald  mines  of  Tako- 
waja  in  the  Catherine  Mountains. 

This  wonderful  stone  is  emerald-green 
to  dark-green  in  color,  with  often  a  slight 
red  tint,  but  by  artificial  light  the  green 
of  good  specimens  changes  to  a  beautiful 
columbine-red. 

As  the  colors  green  and  red  are  the 
national  colors  of  Russia,  and  the  date  of 
discovery  of  this  stone  in  Russia  occurred 
on  the  Emperor's  birthday,  the  name 
alexandrite  was  given  to  this  species  of 
chrysoberyl. 

The  alexandrite  is  found  in  large  pieces, 
but  is  nearly  always  flawed  and  cracked. 
This  is  a  much-sought-after  gem  stone, 
and  specimens  of  from  one  to  five  carats 
command  good  prices.  Up  to  the  present 
time,  however,  good  alexandrites  have 
been  rare,  and  the  demand  has  always  ex- 
ceeded the  supply. 

Cat's-eyes  and  cymophanes  are  found  in 
Brazil  in  alluvial  deposits  of  rivers,  and 
consequently  in  rolled  and  rubbed  masses. 


58  PRECIOUS  STONES. 

Chrysoberyls  are  also  found  in  Russia, 
Germany,  America,  Borneo,  Pegu,  and 
Moravia. 

Chrysolites  and  topazes  are  sometimes 
passed  off  for  chrysoberyls.  The  chryso- 
lite is,  however,  lighter  and  softer,  while 
the  topaz  becomes  electric  from  heating, 
and  is  softer. 

Quartz  cat's-eyes,  which  are  mistaken 
for  chrysoberyl  or  Oriental  cat's-eyes,  have 
a  specific  gravity  of  about  2.65,  hardness 
of  6  to  6.5,  and  are  soluble  in  fluoric  acid, 
besides  melting  with  soda  into  a  clear 
glass. 

They  lack  the  bright,  hard  polish  of  the 
chrysoberyl  cat's-eye,  and  there  should  be 
no  difficulty  in  discovering  the  difference 
between  the  gem  and  the  inferior  stone. 

ZIRCON. 

The  zircon,  hyacinth,  jacinth,  or  jargoon 
belong  to  the  tetragonal  system  of  crys- 
tallization. The  cleavage  is  imperfect, 


ZIRCON.  59 

fracture  conchoidal,  and  specific  gravity 
4.4  to  4.7,  the  stone  being  much  heavier 
than  any  other  gems.  Its  hardness  is  7.5 
and  lustre  vitreous  to  adamantine,  and 
refraction  double  to  a  high  degree. 

The  zircon  is  phosphorescent  when 
heated  ;  before  the  blow-pipe  it  is  infusible, 
but  loses  its  color;  and  with  borax  it  melts 
into  a  transparent  glass.  Sulphuric  acid 
affects  this  gem  after  long  maceration. 

The  composition  of  the  zircon  is  :  zir- 
conia,  66.3  ;  silica,  33.7  ;  with  a  trace  of 
peroxide  of  iron. 

Under  the  microscope,  the  texture  of 
these  gems  presents  a  watery  appearance, 
called  by  the  French  rating  and  which 
looks  like  a  liqueur  poured  into  water. 
This  is  a  strong  distinguishing  point  in  the 
zircon. 

The  zircon,  hyacinth,  jargoon,  and  ja- 
cinth are  the  same  gems  but  of  different 
colors. 

The  brown,  violet,  and  green  colors  are 
known  as  zircons,  the  red  as  hyacinth,  the 


60  PRECIOUS  STONES. 

yellow  as  jacinth,  and  the  grayish-white 
and  white  as  jargoons. 

The  jargoon  has  often  been  palmed  off 
as  a  diamond  because  of  its  transparent 
color  and  adamantine  lustre. 

The  zircon  is  found  in  Ceylon,  Germa- 
ny, France,  Bohemia,  America,  and  in  fact 
in  nearly  all  parts  of  the  earth,  as  many  as 
1 20  localities  having  been  noted  where 
specimens  of  the  mineral  have  been  dis- 
covered. 

The  zircon  can  be  distinguished  from 
the  garnet  by  its  peculiar  diamond-like 
brilliancy  and  its  specific  gravity. 

TURQUOIS. 

The  turquois  is  never  found  in  crystals, 
but  in  reniform  or  stalactitic  masses.  The 
color  varies  from  pea-  and  apple-green  to 
greenish-blue,  sky-blue  and  dark-blue. 

The  hardness  of  the  turquois  is  6., 
specific  gravity  2.6  to  2.8,  lustre  waxy,  and 
condition  opaque  to  slightly  translucent. 


TURQUOIS.  6 1 

Before  the  reducing  flame  of  the  blow- 
pipe, the  turquois  does  not  melt,  but  be- 
comes brown  and  colors  the  flame  green. 
With  borax  and  salts  of  phosphorus  the 
turquois  melts  to  a  clear  glass,  while  it  is 
also  soluble  in  hydrochloric  acid.  Orien- 
tal or  mineral  turquois  is  composed  of : 

Alumina      ....  47.45 
Phosphoric  acid    .     .27.34 

Water 18.18 

Oxide  of  copper    .     .  2.02 

Iron i.io 

Oxide  of  manganese  .  0.50 

Phosphate  of  lime      .  3.41 


The  best  color  is  a  clear  deep  sky-blue, 
and  in  the  true  turquois  this  color  improves 
by  artificial  light ;  imitation  turquoises, 
however,  lose  their  fine  color  under  the 
same  conditions. 

The  finest  gem  turquoises  come  from 
the  northeastern  part  of  Persia,  between 
Nishapoor  and  Meshed.  Here  they  are 
mined  and  partly  cut,  and  then  the  Persian 
merchants  carry  them  to  Russia,  where 


62  PRECIOUS  STONES. 

they  are  sold  at  the  great  annual  fair  of 
Nijni-Novgorod  and  in  Moscow.  Mineral 
turquoises  are  also  found  in  New  Mexico, 
Arizona,  and  Nevada,  but  not  of  sufficient 
size  or  sufficiently  good  color  to  make 
gem  stones,  although  they  are  prized  for 
collections.  Specimens  are  also  found  in 
Burmah,  Khorassan,  Thibet,  China,  Sile- 
sia, Saxony,  and  on  the  Isthmus  of  Suez. 
The  stones  from  these  places  have,  as  a 
rule,  but  little  value,  as  the  color  fades  or 
turns  green  from  exposure  to  the  light.  Of 
late  however,  some  very  good  turquoises 
have  come  from  Egypt.  The  color  of  a 
faded  Persian  turquois  can  sometimes  be 
restored  by  simply  repolishing  the  stone. 

Occidental  or  bone  turquoises  called 
new  rock  or  odontolites,  to  distinguish 
them  from  the  Persian  or  old  rock  stones, 
are  of  organic  origin. 

They  are  cut  from  the  teeth  of  mam- 
moths, mastodons,  dinotheriums,  etc.,  and 
are  found  near  the  town  of  Simor,  in 
Lower  Languedoc,  France. 


TURQUOIS.  63 

These  teeth,  the  enamel  of  which  is 
nearly  as  hard  as  the  mineral  turquois, 
are  colored  by  contact  with  phosphate  of 
iron  and  copper,  which  gives  them  a  dark- 
blue,  light-blue,  and  bluish-green  color. 
They  are  easily  attacked  by  a  file,  and 
totally  destroyed  by  aqua-fortis. 

When  heated,  the  fossil  turquois  or 
odontolite  gives  an  offensive  odor,  owing 
to  the  decomposition  of  animal  matter. 

The  odontolite  is  lighter  than  the  min- 
eral turquois,  changes  color  by  artificial 
light,  loses  color  in  distilled  water  and 
alcohol,  and  is  translucent  on  the  edges. 

This  fossil  turquois  does  not  fade  like 
the  mineral  turquois,  but  by  artificial  light 
appears  of  a  dirty  grayish-blue. 

Turquoises  are  sometimes  artificially 
stained,  but  this  can  be  detected  by 
applying  a  drop  of  ammonia  to  the  back 
of  the  stone,  and  if  the  color  is  artificial 
the  ammonia  will  eat  it  off,  leaving  a 
green  spot.  Ammonia  does  not  affect  the 
color  of  the  Persian  turquois.  The  so- 


64  PRECIOUS  STONES. 

called  "  reconstructed  "  turquoises  are  very 
close  imitations  of  the  real,  but  are  easily 
distinguished,  as  they  change  rapidly  to  a 
deeper  blue  when  immersed  in  water,  and 
while  wet  the  surface  of  the  stone  shows 
cracks  in  every  direction.  These  stones 
become  softer  through  soaking  in  water  or 
alcohol.  The  original  color,  however, 
returns  when  the  stone  is  dry,  but  the 
cracks  remain  in  faint  outline. 

TOURMALINE. 

The  tourmaline  or  precious  schorl  [9 
known  under  many  different  names,  and 
no  other  mineral  has  such  a  suite  of  colors. 

The  colorless  variety  is  known  as 
achroite ;  the  red,  as  rubellite  or  siberite ; 
the  blue,  indicolite  or  Brazilian  sapphire ; 
the  green,  Brazilian  emerald  ;  and  the 
yellowish-green,  Ceylon  chrysolite  or 
Ceylon  peridot.  Besides  the  above  colors 
and  their  shadings,  the  tourmaline  occurs 
in  black  and  brown. 


TO  URMA  LINE.  65 

The  crystallization  is  obtuse  rhomboid, 
and  generally  forms  six-,  nine-,  and  twelve- 
sided  prisms. 

Some  of  the  crystals  are  very  large, 
specimens  over  eight  inches  long  having 
been  mined. 

The  tourmaline  crystals  are  remarkable 
for  their  varied  and  beautiful  groupings  of 
colors.  Some  are  internally  blue  or  brown, 
surrounded  by  a  bright  carmine  red  or 
dull  yellow ;  others  are  red  internally  and 
are  enveloped  by  a  green  exterior ;  crystals 
are  sometimes  pink  at  the  summit  and 
light  green  at  the  base,  or  crimson  tipped 
with  black,  or  white  at  one  end  shading 
into  green  and  finally  into  red  at  the  other 
end.  The  hardness  of  the  tourmaline  is 
7  to  7.5,  specific  gravity  3  to  3.1,  and 
lustre  vitreous. 

The  tourmaline  becomes  decidedly 
electric  by  heating  or  rubbing,  and  will 
readily  attract  small  pieces  of  paper  and 
other  small  objects.  The  rubellite  or  red 
tourmaline  is  composed  of: 


66  PRECIOUS  STONES. 

Silica 42.13 

Alumina 36.43 

Boracic  acid 5.74 

Oxide  of  manganese     .     .     6.32 

Lime 1.20 

Potash 2.41 

Lithia 2.04 

The  green  tourmaline  is  composed  of 

Silica 40. 

Alumina 39. 16 

Lithia  and  potash  .  .  .  3.59 
Protoxide  of  iron  .  .  .  5.96 
Protoxide  of  manganese  .  2. 14 
Boracic  acid  .  .  .  .  .  4.59 
Volatile  matter  .  .  .  .  1.58 


The  tourmaline  possesses  double  refrac- 
tion to  a  high  degree,  and  its  power  of 
polarizing  light  is  so  great  that,  cut  into 
slices,  it  is  used  in  the  polariscope  for 
analyzing  other  minerals. 

If  two  slices  of  tourmaline,  cut  parallel 
to  their  axis,  be  laid  one  on  the  other  in 
one  direction,  both  are  transparent ;  if 
laid  in  another  direction  they  become 
opaque,  and  if  a  doubly  refracting  crystal 
be  placed  between  the  two  plates  of 


TO  URMA  LINE.  6? 

tourmaline,  the  part  covered  by  the  crystal 
is  transparent  while  the  other  is  opaque. 

Tourmaline  melts  with  borax  into  a 
transparent  glass  ;  the  rubellite  turns 
white,  and  the  indicolite  and  green  tour- 
malines turn  black,  under  the  blow-pipe. 

Tourmalines  can  be  distinguished  from 
othergems  by  theirspecific  gravity, but  prin- 
cipally by  their  property  of  assuming  po- 
laric  electricity  after  being  heated,  one  end 
becoming  positive  and  the  other  negative. 

The  history  of  the  discovery  of  the 
tourmaline  and  its  electric  property  is  a 
curious  one. 

On  a  warm  summer  day,  early  in  the 
eighteenth  century,  some  children  were 
playing  in  a  courtyard  in  Amsterdam. 
Amongst  their  playthings  were  some  pre- 
cious stones  which  the  Dutch  navigators 
had  brought  from  Ceylon.  Some  of  the 
stones  seemed  to  be  possessed  of  the 
strange  power  of  attracting  and  repelling 
small  bits  of  straw,  ashes,  and  other  light 
substances.  The  little  ones  called  their 


68  PRECIOUS  STONES. 

parents  to  witness  this  strange  phenom- 
enon, and  the  stolid  Dutch  lapidaries, 
themselves  puzzled  at  the  sight,  called  the 
stones  aschentreckers  or  ash-drawers. 

A  number  of  years  afterwards,  careful 
experiments  disclosed  the  wonderful  elec- 
tric powers  of  the  aschentreckers  or  tour- 
malines. Purple,  green,  and  blue  tour- 
malines are  found  in  Brazil.  In  Ceylon 
the  stones  are  found  in  gravel  beds.  Ru- 
bellites  or  siberites  are  found  in  Siberia. 

Tourmalines  are  also  found  in  Moravia, 
the  island  of  Elba,  Sweden,  Burmah, 
Tyrol,  Canada,  and  the  United  States. 

The  first  tourmaline  deposits  known  in 
the  United  States  were  discovered  at  Paris, 
Maine,  in  1820.  Another  wonderful  de- 
posit was  found  at  Mt.  Apatite  in  Maine 
in  1882,  and  up  to  the  present  time  the 
finest  tourmaline  crystals  have  been  dis- 
covered in  the  United  States. 

Really  fine  specimens  of  red,  blue,  or 
green  tourmalines  are  uncommon  and  com- 
mand very  good  prices. 


OPAL.  69 

OPAL. 

The  precious  or  noble  opal,  fire  opal, 
common  opal,  hydrophane,  and  cachelong 
are  different  varieties  of  a  mineral  that  is 
composed  of  about  nine  parts  silica  and 
one  part  water. 

The  colors  vary  from  chalky-white  to 
bluish-white,  from  yellow  to  red,  and  from 
a  slight  play  of  colors  to  the  beautiful 
mingling  of  green,  blue,  and  red  with  the 
most  remarkable  kaleidoscopic  effects. 

The  opal  is  5.5  to  6  in  hardness,  specific 
gravity  2  to  2.1,  lustre  glassy,  and  trans- 
lucent from  a  slight  to  a  very  high  degree. 

The  opal  is  found  in  an  amorphous 
state  and  never  crystallizes ;  in  fact  from 
the  condition  of  the  pockets  in  which  this 
mineral  is  found,  the  indications  are  that 
the  substance  was  once  a  fluid. 

Under  the  blow-pipe  the  opal  loses  its 
translucency  and  cracks  but  does  not  melt. 
Sulphuric  acid  will  cause  it  to  turn  black, 
and  in  a  cold  solution  of  caustic  potash 
the  opal  is  almost  entirely  soluble. 


7O  PRECIOUS  STONES. 

The  precious  or  noble  opal  is  found 
chiefly  in  the  mines  of  Czernowitza,  be- 
tween Kaschau  and  Eperies,  in  Hungary, 
and  in  Gracias  a  Dios,  a  province  in 
Honduras. 

In  olden  times,  the  Greek  and  Turkish 
merchants  carried  opals  from  Hungary  to 
the  Orient,  and  then  they  were  shipped  to 
Holland  and  sold  in  Europe  as  Oriental 
opals. 

The  fire  opal  is  of  a  yellowish-red  color, 
and  is  found  chiefly  in  Mexico,  although 
it  also  occurs  in  Hungary,  the  Faroe 
Islands,  Honduras,  and  Guatemala. 

The  common  opal  is  found  in  Ireland, 
Denmark,  Frankfurt,  Guatemala,  and 
South  Australia,  and  also  in  Hungary 
and  Mexico.  These  opals  are  translucent 
without  fire  or  reflection. 

The  hydrophane  is  an  opal  that  has  lost 
color  and  brilliancy  by  reason  of  the 
evaporation  of  its  water.  If  placed  in 
water  or  alcohol,  this  stone  becomes  trans- 
parent, only  to  lose  this  quality  when  the 
water  or  alcohol  has  evaporated. 


PEARL.  71 

The  hydrophane  becomes  transparent 
more  quickly  in  warm  than  in  cold  water, 
but  most  rapidly  in  alcohol.  If  boiled  in 
oil,  the  hydrophane  is  said  to  retain  its 
brilliancy  for  years. 

The  cachelong  is  milky-white,  and 
nearly  opaque,  and  is  found  in  small 
masses  in  the  river  Cach,  in  Bucharia, 
and  also  in  Iceland. 

Although  one  of  the  most  magnificent 
of  the  gem  stones,  the  opal  for  many 
years  was  under  the  ban  of  superstition. 
Now,  this  splendid  stone  once  more  com- 
mands a  foremost  place  in  the  jewelers' 
art,  and  the  opal  mines  of  Hungary  and 
Queensland  are  being  worked  to  their 
fullest  extent  to  supply  the  demand. 

PEARL. 

Although  an  organic  product,  the  pearl 
is  always  ranked  amongst  the  most 
precious  of  gems,  and  is  distinguished  by 
being  the  only  gem  that  does  not  require 
the  lapidary's  touch  to  bring  out  its 
beauties. 


72  PRECIOUS  STONES. 

Ancient  writers  have  accounted  for  the 
origin  of  pearls  by  saying  that  they  were 
formed  of  angels'  tears,  or  drops  of  dew 
from  heaven,  which,  during  the  midsum- 
mer nights,  fell  into  the  gaping  mouths  of 
the  pearl-oysters. 

According  to  modern  scientific  investi- 
gation, the  formation  of  the  pearl  does 
not  seem  to  be  the  result  of  healthy 
natural  causes,  but  comes  from  the  efforts 
of  the  oyster  to  rid  itself  of  some  foreign 
substance,  like  a  grain  of  sand,  a  bit  of  shell 
or  vegetation,  or  some  unwelcome  visitor 
in  the  shape  of  a  small  water  insect. 

When  annoyed  by  an  intruding  sub- 
stance, the  oyster  begins  to  deposit  its 
nacre,  or  mother-of-pearl,  in  regular  con- 
centric layers  around  the  intruder,  these 
layers  gradually  increasing  in  circumfer- 
ence and  forming  the  pearl.  Thus,  like 
an  onion,  the  pearl  is  merely  a  succession 
of  layers  or  skins,  starting  from  a  small 
core;  or  nucleus,  which  is  always  present, 
though  often  only  of  microscopical  size. 


PEARL.  73 

Pearls  have  sometimes  been  found 
where  the  outer  layer,  or  skin,  as  it  is 
technically  called,  has  been  discolored  or 
otherwise  injured,  and  when  this  top  skin 
has  been  carefully  removed  the  result  was 
a  somewhat  smaller  but  perfect  pearl. 

This,  however,  is  a  very  delicate  opera- 
tion, and  at  the  pearling  grounds  is  only 
resorted  to  by  men  of  experience.  The 
composition  of  the  pearl  is  carbonate  of 
lime,  with  a  small  proportion  of  organic 
matter,  and  the  specific  gravity  2.5  to 
2.7. 

The  pearl  is  affected  by  acids,  and  is 
easily  calcined  on  exposure  to  heat. 

In  color,  the  pure  white,  slightly  trans- 
parent, is  the  most  highly  prized  ;  while  in 
India  and  China  the  bright  yellow  colors 
are  sought  after. 

Decided  colors,  however,  such  as  black, 
pink,  and  golden-yellow  bring  a  high 
price,  and,  in  fact,  black  pearls,  if  perfect 
in  color  and  shape,  are  at  present  more 
valuable  than  any  other  kind. 


74  PRECIOUS  STONES. 

The  beauty  and  value  of  a  pearl  de- 
pend on  form,  quality  of  texture  or  skin, 
color,  transparency  or  water,  and  lustre  or 
orient. 

In  form,  the  perfectly  round  shape  comes 
first  in  value,  then  a  finely  formed  drop  or 
pear  shape,  and  lastly  the  oval  or  egg  shape. 

Pearls  that  are  flat  on  one  side  and 
rounded  on  the  other  are  called  boutons 
or  button  pearls.  These  are  frequently 
found  attached  to  the  shell,  and  are  cut 
out  and  the  bottom  part  smoothed  and 
polished. 

It  is  easy,  however,  to  detect  this  class 
of  pearls  by  the  lack  of  pearly  lustre  on 
the  side  that  was  attached  to  the  shell. 

When  a  pearl  is  rough  and  odd-shaped 
it  is  called  a  baroque,  and  some  extremely 
fantastic  shapes  are  found,  especially  in 
fresh-water  oysters. 

The  texture  or  skin  of  a  fine  pearl 
should  be  perfectly  smooth  and  free 
from  all  spots,  indentations,  wrinkles,  or 
scratches. 


PEARL.  75 

Pure  white  is  the  desirable  color  for 
a  gem  pearl,  but  many  others  that  are 
slightly  tinted  with  blue,  pink,  or  yellow 
will  pass  for  gems  if  they  are  otherwise 
perfect. 

The  transparency  or  "  water "  of  a 
pearl,  while  not  existing  in  fact,  is  still 
one  of  the  requisites  of  a  fine  pearl ;  there 
must  be  an  appearance  of  transparency, 
which  adds  to  the  beauty  of  the  gem. 

To  describe  the  lustre  or  orient  of  the 
pearl,  the  author  can  only  use  the  term 
pearly,  as  there  is  no  other  substance  that 
approaches  the  brilliancy  and  color  of  a 
pearl,  excepting,  of  course,  mother-of- 
pearl — the  nacre  in  the  pearl-oyster. 

Without  orient  or  lustre,  the  pearl  of 
finest  form  and  color  has  but  little  value. 

Lustre  is  to  the  pearl  what  brilliancy  is 
to  the  diamond  ;  when  the  orient  is  ab- 
sent there  is  no  life,  no  beauty. 

Pearls  are  principally  supplied  by  two 
groups  of  pearl-oysters  or  mussels:  the 
marine  or  meleagrina  margaritifera,  a 


76  PRECIOUS  STONES. 

round-cornered  square  shell  with  very 
thick  sides,  measuring  six  to  eight  inches 
in  length. 

The  color  of  this  shell  is  mostly  black- 
ish-green, but  it  is  also  sometimes  yellow- 
ish ;  the  edges  of  the  inner  part  of  the 
shell  are  black,  but  the  rest  of  the  interior 
is  the  beautiful  mother-of-pearl. 

The  oyster  itself  is  small  for  the  size  of 
the  shell. 

This  specimen  is  found  on  the  coast  of 
Ceylon,  Persian  Gulf,  Japanese,  Mexi- 
can and  California  coasts,  the  western 
shores  of  South  America,  Brazil,  West 
Indian  Islands,  Panama,  Sooloo  Archi- 
pelago, and  the  northeast  and  northwes- 
tern coast  of  Australia. 

The  fresh-water  or  unio  margaritifera 
is  an  even,  egg-shaped  mussel  found  in 
brooks,  rivers,  and  lakes  in  temperate 
zones  in  nearly  all  parts  of  the  world. 

Some  fine  river  pearls  have  been  found 
in  the  United  States,  but  most  of  the 
American  pearls  are  of  a  button  or  elon- 


PEARL.  77 

gated  shape,  or  are  baroques  or  fancy- 
shaped. 

In  China  many  people  engage  in  the 
business  of  making  small  pellets  of  clay 
or  metal  images,  which  in  the  month  of 
May  are  introduced  into  the  river  mussels 
(mytilus  cygneus). 

The  mussels  are  replanted,  and  in  No- 
vember they  are  taken  up  again.  Some 
of  the  oysters  die,  but  most  of  them  are 
found  to  have  been  actively  at  work  cov- 
ering the  little  pellets  or  metal  figures 
with  nacre,  and  while  no  strictly  first-class 
pearls  are  formed  in  this  way,  many  curious 
little  pearl  figures  or  gods  are  made  and 
sold  to  the  curious  or  devout. 

Pink  or  conch  pearls  are  found  in  the 
Gulf  of  California  and  coasts  of  Mexico, 
Bahama  Islands,  West  Indian  Islands,  and 
in  some  rivers  in  South  America. 

They  seldom  occur  in  regular  shapes, 
and  although  they  are  termed  pink  pearls, 
they  range  in  color  from  red  to  pale  yellow, 
and  are  often  found  of  a  china-white  color. 


78  PRECIOUS  STONES. 

The  pink  pearl  displays  a  wavy  appeal 
ance  and  a  peculiar  sheen,  something  like 
watered  silk.     As  the  pink  pearl  is  seldom 
found  perfectly  round  and  of  a  good  color, 
such  a  specimen  is  very  valuable. 

CHRYSOLITE. 

The  chrysolite,  peridot,  and  olivine  dif- 
fer in  color,  but  are  practically  of  the  same 
composition. 

The  chrysolite  proper  is  of  a  pale  green- 
ish-yellow color,  the  peridot  a  deep  olive- 
green,  and  the  olivine  of  a  yellowish  or 
light  olive-green  color ;  these  stones  also 
shade  into  brown.  They  crystallize  on 
the  rhombic  system,  are  tranparent  to 
translucent,  6.5  to  7.  in  the  scale  of  hard- 
ness, and  3.3  to  3.5  in  specific  gravity. 

The  cleavage  is  distinct,  fracture  con- 
choidal,  refraction  double,  and  lustre 
vitreous,  and  in  the  olivines  somewhat 
greasy. 

These  stones  are  easily  affected  by  sul- 
phuric acid,  but  are  infusible  before  the 


CHR  YSOLITE.  79 

blow-pipe,  excepting  some  kinds  contain- 
ing much  iron. 

With  borax,  they  melt  to  a  pale-green 
transparent  glass. 

Chrysolites  are  composed  of  silica, 
magnesia,  and  oxide  of  iron. 

Perfectly  crystallized  chrysolites  are 
brought  from  Constantinople,  but  the 
exact  locality  where  they  are  found  is 
unknown. 

Less  distinct  specimens  occur  at  Vesu- 
vius, Mexico,  the  isle  of  Bourbon,  Au- 
vergne,  Egypt,  Natolia,  Brazil,  Germany, 
Pegu,  Ceylon,  Switzerland,  and  North 
America. 

Peridots  are  distinguished  by  being  the 
only  precious  stones  that  have  literally 
dropped  from  heaven,  as  they  have  been 
found  in  meteorites. 

The  Oriental  chrysolite  of  commerce  is 
true  chrysoberyl,  and  is  harder  and 
heavier  than  chrysolite,  and  the  stone 
called  Ceylon  chrysolite  is  a  greenish- 
yellow  tourmaline,  which  is  easily  dis- 


8O  PRECIOUS  STONES. 

tinguished,  as  it  is  also  harder  while  con- 
siderably lighter  than  the  chrysolite. 

The  green  garnet  is  of  a  pronounced 
green  color,  and  is  harder  and  heavier 
than  the  olivine  or  chrysolite.  Although 
suitable  for  mounting  in  brooches  and 
other  ornaments,  these  stones  are  not 
sufficiently  hard  for  the  rough  usage  as 
ring-stones. 

GARNET. 

Almandine,  almandite,  Syrian  garnet, 
essonite,  cinnamon-stone,  pyrope,  Bohe- 
mian garnet,  vermeille,  Cape  garnet,  Cape 
ruby,  Arizona  ruby,  American  ruby,  car- 
buncle, uwarowite,  demantoide,  grossula- 
rite,  and  Bobrovvska  garnet  are  some  of 
the  scientific  and  commercial  names  for 
different  species  and  colors  of  the  garnet 
group. 

The  crystallization  of  the  garnet  is  iso- 
metric, refraction  single,  specific  gravity 
3.15  to  4.3,  hardness  5  to  8,  lustre  vitreous, 
fracture  uneven,  colors  red,  violet,  brown, 


GARNET.  8 1 

yellow,  green,  and  white,  and  the  various 
shadings  of  these  colors. 

Most  varieties  fuse  easily  to  a  brown  or 
black  glass ;  the  uwarowite  fuses  with 
borax  to  a  clear  chrome-green  glass. 

Syrian,  almandine,  almandite,  and  car- 
buncle are  different  names  for  the  iron- 
alumina  garnet. 

In  colors,  these  stones  shade  from  deep- 
red  to  violet  and  brownish-red,  and  are 
composed  of : 

Silica 36.01 

Alumina 20.06 

Protoxide  of  iron  .     .     .     43.03 

The  specific  gravity  is  4.  to  4.2,  and 
hardness  7.5. 

This  garnet,  sometimes  called  the 
precious  garnet,  is  found  in  Ceylon,  Pegu, 
Brazil,  Greenland,  Hindustan,  Bohemia, 
Tyrol,  QEtzthal,  Carinthia,  Styria,  Switz- 
erland, Ariolo,  Canaria,  Maggia,  Hungary, 
Sweden,  Norway,  Scotland,  Spain,  and 
the  United  States. 


82  PRECIOUS  STONES. 

Grossularite,  or  lime-alumina  garnet,  is 
known  in  commerce  as  essonite,  or  cinna- 
mon-stone. The  color  is  yellow,  of  various 
shades  ;  specific  gravity  3.5  to  3.65,  and 
hardness  6.5. 

These  stones  are  sometimes  sold  for 
jacinths,  but  they  are  softer  than  the 
jacinth,  and  melt  easily  before  the  blow- 
pipe. Essonites  come  principally  from 
Ceylon,  but  are  also  found  in  other  places. 

Pyrope  or  Bohemian  garnet  is  the  mag- 
nesia-alumina variety,  and  is  of  a  uniform 
dark  blood-red  color.  This  stone  is  found 
in  Bohemia,  and  although  quantities  of 
small  pieces  are  found,  large  specimens 
are  rare,  and  a  piece  that  will  cut  into 
a  four-  or  five-carat  stone  is  seldom  met 
with  and  commands  a  high  price. 

These  garnets  are  found  at  Stiefelburg 
by  Meronitz,  Triblitz,  Podsedlitz,  and 
Neupaka. 

The  pyrope  turns  black  under  the  blow- 
pipe, then  red  again,  and  melts  with  diffi- 
culty into  a  black  glass.  With  borax  it 


GARNET.  83 

melts  to  an  emerald-green  glass.  The 
specific  gravity  of  this  garnet  is  3.69  to 
3.78,  and  hardness  7.5. 

Vermeille  is  a  name  given  to  the  orange- 
red  almandine,  Cape  garnet  to  the  bright 
red-yellow  variety,  Cape  ruby  to  the  pyr- 
ope,  and  American  ruby  tc  the  blood-red 
kind  found  in  New  Mexico,  Montana,  and 
Arizona.  Carbuncle  is  a  term  applied  to 
all  garnets  cut  with  a  smooth  rounding 
top,  sometimes  called,  after  the  French, 
cabochon. 

Uwarowite  or  lime-chrome  garnet  is  one 
of  the  rarest  and  most  beautiful  of  the 
garnet  group. 

The  color  of  this  stone  is  emerald-green, 
hardness  7.5,  and  specific  gravity  3.41  to 
3.52.  Uwarowites  are  found  near  Bissersk 
in  the  Urals  of  Russia,  but  rarely  in  speci- 
mens of  sufficient  size  to  cut  into  gems. 

This  garnet  is  heavier  and  harder  than 
the  true  emerald. 

Demantoide  or  Bobrowska  garnet  is  a 
soft  garnet,  olive-green  to  brown  and 


84  PRECIOUS  STONES. 

blackish-green  in  color,  sometimes  light 
green.  It  is  found  in  the  Bobrowska 
River  in  the  Urals.  The  specific  gravity 
is  3.85,  and  hardness  about  6,  its  softness 
making  it  undesirable  for  many  ornaments. 
Before  the  blow-pipe  it  fuses  into  a  black 
bead. 

These  garnets  are  often  sold  as  olivines ; 
they  are  heavier  than  olivines  and  softer. 

Demantoide  is  composed  of : 

Silica 35.44 

Lime 32.85 

Sesquioxide  of  iron     .     .     32.85 
Magnesia 20 

TOPAZ. 

Topaz  belongs  to  the  rhombic  system 
of  crystallization.  Its  cleavage  is  basal 
and  perfect,  fracture  uneven,  hardness  8, 
scratching  quartz  distinctly,  specific  grav- 
ity 3.4  to  3.6,  lustre  vitreous,  refraction 
double,  and  colors  ranging  from  colorless 
or  white  to  bluish-white,  light  blue,  wine- 
yellow,  straw-yellow,  golden-yellow,  green- 
ish- and  pale-red  to  pink. 


TOPAZ.  85 

Topaz  becomes  electric  from  rubbing 
or  pressure,  and  retains  electricity  for 
twenty-four  hours.  Before  the  blow-pipe 
topaz  partly  loses  color,  but  does  not  melt, 
and  with  borax  it  fuses  slowly  to  a  white 
bead. 

Topaz  is  partially  attacked  by  sulphuric 
acid,  and  dissolves  in  salts  of  phosphorus. 

The  composition  of  topaz  is  : 

Silicon !5-O5 

Aluminium 30.02 

Oxygen 36.08 

Fluorine 17.05 

Goutte  d'eau  or  colorless  topaz,  some- 
times called  "  slaves  diamond,"  Siberian 
or  bluish-white,  Brazilian  or  golden  to 
reddish-yellow,  Saxony  or  pale-wine  yel- 
low, Brazilian  ruby  or  pink,  Brazilian 
sapphire  or  light  blue,  and  aquamarine  or 
greenish,  are  the  various  commercial  names 
for  topaz. 

Most  of  the  Brazilian  rubies  or  pink 
topazes  are  produced  by  heating  the  red- 
dish or  dark-yellow  variety,  either  in  a 
crucible  or  by  enveloping  the  stone  in 


86  PRECIOUS  STONES. 

German  tinder  and  setting  fire  to  the  tin- 
der. If  heated  too  much,  the  stone  is  apt 
to  become  colorless,  and  if  suddenly  cooled 
it  may  crack. 

Colorless  or  white  topaz  takes  a  very 
high  polish,  and  is  wonderfully  clear  and 
transparent. 

The  great  Portuguese  diamond,  "  The 
Braganza,"  of  about  1,680  carats,  is  sup- 
posed to  be  a  white  topaz. 

Topaz  is  found  in  the  Urals,  Kam- 
schatka,  Alabaschka,  Miask,  Nestschinsk, 
Adun  Tschilon,  Villa  Rica,  Boa  Vista, 
Capao,  Lana,  Minas  Novas,  Cairngorm 
Mts.,  Schlackenwald,  Zinnwald,  Schneck- 
enstein,  Ehrenfriedensdorf,  Altenburg, 
Orenburg,  Mourne  Mts. — Ireland,  Aus- 
tralia, New  South  Wales,  Ceylon,  Mexico, 
and  the  United  States.  False  topaz,  or 
the  ordinary  topaz  of  commerce,  is  yellow 
quartz  resembling  yellow  topaz,  but  lack- 
ing its  brilliancy  and  hardness ;  it  is  also 
very  much  lighter,  being  only  2.5  to  2.7 
in  specific  gravity. 


APA  TITE.  87 

Beryl  and  chrysolite  are  often  mistaken 
for  topaz,  but  as  they  are  softer  and  beryl 
is  much  lighter,  they  are  easily  distin- 
guished from  the  topaz.  The  strong  elec- 
tric property  of  the  topaz  is  also  a  con- 
clusive test. 

Oriental  topaz,  or  yellow  corundum,  is 
harder  and  heavier  than  the  occidental  or 
true  topaz. 

APATITE. 

Apatite,  which  is  seldom  used  as  a  gem 
stone,  sometimes  resembles  the  beryl  and 
emerald,  but  is  much  softer  and  rarely  has 
the  color  and  brightness  combined  of  the 
former  gems. 

This  mineral,  composed  principally  of 
subsesquiphosphate  of  lime,  is  4.5  to  5.  in 
hardness,  has  the  specific  gravity  of  2.95 
to  3.25,  is  transparent  to  opaque,  vitreous 
in  lustre,  infusible  before  the  blow-pipe, 
and  dissolves  slowly  in  nitric  acid.  In 
colors,  apatite  varies  from  colorless  to  sea- 


88  PRECIOUS  STONES. 

green,  bluish-green,  violet-blue,  gray,  yel- 
low, red,  and  brown. 

Apatite  is  found  in  Saxony,  the  Hartz 
Mts.,  Bohemia,  Norway,  Bavaria,  England, 
St.  Gothard  in  Switzerland,  and  in  the 
United  States. 

FELSPAR. 

Four  varieties  of  felspar  are  used  as  gem 
stones — moonstone  or  orthoclase,  sun- 
stone  or  avanturine  felspar,  Amazon  stone 
or  greerftelspar,  and  Labrador  or  Labrador 
spar. 

MOONSTONE. 

This  variety  of  felspar  is  called  ortho- 
clase, adularia,  and  orthose,  besides  the 
commercial  names  of  fish-eye,  Ceylon  or 
water  opal,  and  in  the  yellow  and  red  tints 
sunstone.  Moonstone  occurs  in  crystals 
and  crystalline  fragments,  also  massive  and 
granular;  its  hardness  is  6.  to  6.5,  specific 
gravity  2.4  to  2.6,  refraction  double,  is  not 
attacked  by  acids,  and  is  composed  of : 


MOONSTONE.  89 

Silica 64.5 

Alumina 18.5 

Potash 17. 

With  traces  of  soda. 

This  beautiful  stone  is  the  clearest  of  all 
varieties  of  felspar.  It  is  colorless,  or  only 
slightly  tinted  with  blue,  green,  yellow, 
and  flesh-red,  and  is  transparent  to  trans- 
lucent. 

The  lustre  is  vitreous,  and  a  brilliant 
pearly  streak  of  white  light  plays  from 
side  to  side. 

The  yellowish-  and  reddish-tinted  speci- 
mens are  called  sunstones,  and  are  quite 
rare.  These  sunstones  must  not  be  con- 
founded with  the  avanturine  or  felspar 
sunstone. 

Moonstones  are  found  principally  in 
Ceylon  and  on  the  St.  Gothard  in  Switzer- 
land, but  also  occur  in  Bavaria,  Green- 
land, Tyrol,  Dauphine,  Norway,  and  the 
United  States. 

During  the  past  few  years,  large  quanti- 
ties of  moonstone  balls,  cut  like  whole 
pearls,  have  been  used  for  jewelry — the 


90  PRECIOUS  STONES. 

stones  being  much  sought  as  well  because 
of  their  beauty  as  on  the  ground  of  the 
popular  superstition  that  they  will  bring 
good  luck  to  the  wearer. 

Small  pieces  or  balls  are  not  very  valu- 
able, but  large  perfect  specimens  command 
a  good  price. 

SUNSTONE. 

(AVANTURINE   FELSPAR.) 

Sunstone  or  avanturine  felspar  is  a 
variety  of  oligoclase ;  grayish-white  to 
reddish-gray  in  color,  usually  the  latter ; 
containing  minute  crystals  of  hematite, 
gothite  or  mica,  which  are  imbedded  and 
scattered  through  the  stone,  and  give 
forth  golden-yellow,  reddish,  or  prismatic 
reflections.  The  hardness  is  6  to  7,  spe- 
cific gravity  2.56  to  2.72,  and  lustre  pearly 
or  waxy  to  vitreous. 

Sunstones  are  found  near  Stockholm, 
in  Finland,  the  Urals,  Ceylon,  the  Alps, 
Iceland,  the  United  States,  and  other 
places. 


AMAZON  STONE.  9! 

AMAZON  STONE. 

(GREEN  FELSPAR.) 

The  Amazon  stone  is  a  green  variety  of 
felspar,  which  was  first  found  on  the 
banks  of  the  Amazon  River,  but  now 
comes  from  Siberia  and  the  United  States. 
This  stone  consists  of  potash,  alumina, 
and  silex — is  green  in  color  but  rarely 
clean,  being  discolored  in  places  and 
usually  covered  with  small  white  spots. 

The  Amazon  stone  is  harder  than  glass, 
but  is  scratched  by  rock  crystal.  Its 
specific  gravity  is  2.5  to  2.6  ;  acids  do  not 
affect  it,  and  it  melts  with  difficulty  before 
the  blow-pipe. 

LABRADORITE. 

Labrador  stone  or  labradorite  is  some- 
times known  as  opaline  felspar,  and  was 
first  discovered  on  the  island  of  St.  Paul 
on  the  coast  of  Labrador. 

Labradorite  is  translucent  to  opaque, 
gray-green  or  brown  in  color,  and  has 


92  PRECIOUS  STONES. 

beautiful  chatoyant  reflections  of  brilliant 
blue,  sea-green,  and  sometimes  red  and 
yellow,  changing  from  one  color  to  another. 
Labradorite  is  6  in  hardness,  has  a  specfiic 
gravity  of  2.62  to  2.76 ;  a  vitreous  to 
pearly  lustre,  is  brittle,  fuses  with  difficulty 
before  the  blow-pipe,  and  is  decomposed  by 
muriatic  acid.  It  is  composed  of : 

Silica 52.9 

Alumina      .     .     .     .  30.3 

Lime 12.3 

Soda 4-5 

Large  masses  of  this  stone  are  found  on 
the  coast  of  Labrador.  It  is  also  found 
in  Finland,  Russia,  and  the  United  States. 
Because  of  the  dark  chatoyant  appearance 
the  name  of  ceil  de  bceuf  or  ox-eye  is 
sometimes  applied  to  labradorite.  Hand- 
some specimens,  cut  cabochon,  form  pretty 
ring  stones,  and  many  effective  engraved 
cameos  have  been  produced  by  using  the 
bright  portion  for  the  relief  work  and  the 
gray  dead  part  for  the  base. 


CYANITE.  93 

CYANITE. 

This  stone  is  the  transparent  variety  of 
disthene,  and  is  sometimes  commercially 
known  as  sappare.  Cyanite  is  colorless  to 
bluish-white,  sky-blue,  berlin  blue,  yellow- 
ish- and  reddish-white,  gray,  and  green. 

The  hardness  is  5  to  7,  specific  gravity 
3.45  to  3.70,  lustre  vitreous  and  pearly; 
it  is  infusible  before  the  blow-pipe,  but 
fuses  with  borax  ;  is  not  attacked  by  acids, 
and  is  composed  of  : 

Silica 36.8 

Alumina      .     .     .     .     63.2 

Cyanite  is  found  in  Switzerland,  the 
Tyrol,  Styria,  Carinthia,  Bohemia,  Nor- 
way, Finland,  France,  South  America, 
Scotland,  Ireland,  Siberia,  the  East  Indies, 
and  the  United  States.  Clean  specimens 
are  not  plentiful,  and  fine  blue  pieces  have 
frequently  been  sold  for  sapphires.  The 
cyanite  can  be  distinguished  from  the 
sapphire  by  its  inferior  hardness  and 
lighter  weight. 


94  PRECIOUS  STONES. 

LAPIS  LAZULI. 

Lapis  lazuli,  the  sapphire  of  the  ancients, 
is  a  mineral,  translucent  to  opaque,  ranging 
in  color  from  colorless  to  an  azure-blue, 
violet-blue,  green,  and  red. 

The  principal  color,  however,  is  a  rich, 
azure  blue,  sometimes  shading  into  green, 
and  having  a  vitreous  to  greasy  lustre. 

Its  hardness  is  5  to  5.5,  specific  gravity 
2.38  to  2.42 ;  it  is  decomposed  by  muri- 
atic acid,  and  fuses  before  the  blow-pipe  to 
a  white  glass.  It  is  rarely  found  clean,  but 
has  usually  a  number  of  veins  and  spots 
of  a  metallic  nature.  It  is  composed  of: 

Silica 45. 

Alumina      .     .     .     .     31.76 

Soda 9.09 

Lime 3.52 

Sulphuric  acid       .     .       5.89 
and  traces  of  iron,  soda,  and  potash. 

This  mineral  is  found  in  Siberia,  Tran- 
sylvania, Persia,  China,  Thibet,  Tartary, 
South  America,  India,  and  Brazil. 

Lapis  lazuli  is  sometimes  employed  for 
jewelry,  and  was  for  some  centuries  ground 


HIDDENITE.  95 

up  and  used  to  make  the  mineral  paint 
known  as  genuine  ultramarine.  This  paint 
is  now  produced  chemically,  and  the  more 
costly  mineral  compound  is  rarely  used. 

The  imitation  of  lapis  lazuli  for  jewelry 
purposes  is  also  very  easy,  as  metal  filings 
can  be  readily  introduced  into  the  azure 
blue  glass,  and  thus  an  imitation  of  the 
genuine  stone  produced,  which  is  perfect 
except  in  hardness. 

HlDDENITE. 

The  hiddenite  is  a  variety  of  spodumene 
that  has  only  been  found  in  one  locality, 
namely  Alexander  County,  North  Caro- 
lina. This  mineral  was  discovered  by  W. 
E.  Hidden,  and  has  been  named  after  him. 

The  hiddenite  is  perfectly  transparent, 
and  varies  from  a  pale  yellowish-  to  a  deep 
emerald-green,  being  very  brilliant,  and 
approaching  the  emerald  in  color.  As  this 
stone  is  rarely  found  large  enough  for  cut- 
ting into  gems,  it  is  highly  prized  and 
good  specimens  command  a  large  price. 


96  PRECIOUS  STONES. 

The  hardness  of  the  hiddenite  is  6.5  to 
7,  and  specific  gravity  3.13  to  3.19 ;  before 
the  blow-pipe  it  melts  to  a  clear  glass,  and 
it  is  attacked  by  salts  of  phosphorus.  It 
is  composed  of: 

Silica 64.35 

Alumina    .     .     .     .     26.58 

Lithia 7.05 

with  traces  of  iron  and  soda. 

SPODUMENE. 

Spodumene  is  sometimes  cut  and  pol- 
ished as  a  gem,  but  its  peculiar  cleavage 
makes  it  a  bad  stone  for  the  lapidary  to 
cut  and  the  jeweler  to  mount. 

Its  hardness  is  6.5  to  7,  specific  gravity 
3.13  to  3.19,  and  lustre,  vitreous  to  pearly. 

Grayish  -  green,  greenish  -  white,  and 
sometimes  yellow  or  faint  red  are  the 
colors.  Its  composition  is : 

Silica 64.2 

Alumina    ....     29.4 
Lithia 6.4 

Acids  do  not  attack  spodumene,  and  un- 
der the  blow-pipe  it  fuses  to  a  white  glass. 


DICHROITE.  97 

This  mineral  is  found  in  Sweden,  the 
Tyrol,  Ireland,  Scotland,  and  the  United 
States. 

DlCHROITE. 

Dichroite  is  sometimes  known  under 
the  mineralogical  names  of  cordierite  and 
iolite,  and  commercially  as  saphir  d'eau^ 
or  water  sapphire.  This  stone  is  remarka- 
ble for  pleichroism,  sometimes  showing 
three  different  colors  in  as  many  direc- 
tions, and  when  properly  cut  has  often 
the  star  formation  of  the  corundum  star- 
stones. 

Water  sapphire,  as  the  blue  specimens 
are  called,  is  7  to  7.5  in  hardness,  specific 
gravity  2.56  to  2.67,  transparent  to  trans- 
lucent, and  frequently  full  of  flaws.  It  is 
partially  decomposed  by  acids,  melts  with 
difficulty  before  the  blow-pipe,  is  vitreous 
to  greasy  in  lustre,  and  is  composed  of : 

Silica 49. 

Alumina    ....  32. 

Ferrous  oxide      .     .  7. 

Magnesia  ....  9. 


98  PRECIOUS  STONES. 

Besides  the  saphir  d'eau,  which  is  blue, 
dichroite  occurs  colorless,  bluish-white, 
yellowish-white,  yellowish-gray  to  yellow- 
ish-brown, indigo  to  blackish-blue,  and 
violet.  This  mineral  is  found  in  Ceylon, 
Spain,  Norway,  Sweden,  Tuscany,  Green- 
land, and  Bavaria.  Sapphire  is  harder 
and  much  heavier  than  dichroite. 

IDOCRASE. 

Idocrase  or  vesuvianite  was  first  found 
amongst  the  ancient  ejections  of  Vesuvius, 
and  it  is  still  found  at  Vesuvius  in  hair- 
brown  to  olive-green  colors. 

Vesuvianite  is  6.5  in  hardness,  3.35  to 
3.45  in  specific  gravity,  transparent  to 
opaque,  lustre  vitreous  to  greasy.  It  pos- 
sesses strong  double  refraction,  is  attacked 
by  acids,  and  melts  readily  under  the 
blow-pipe.  Vesuvianite  consists  of : 

Silica 37-75 

Alumina    .     .     .     .  17.23 

Sesquioxide  of  iron  .  4.43 

Magnesia  ....  3.79 

Lime 37-35 


EU CLASS.  99 

In  colors,  this  mineral  shades  from 
brown  to  black,  yellow,  pale-blue,  and 
green,  and  it  is  found  at  Vesuvius,  Alps, 
Piedmont,  Mt.  Somma,  Etna,  Norway, 
Sweden,  Spain,  Hungary,  Urals,  and  the 
United  States. 

Transparent  or  strongly  translucent 
specimens,  in  handsome  green  or  brown 
varieties,  are  used  for  jewelry,  principally, 
however,  in  Turin  and  Naples. 

Chrysolite  and  green  garnet  are  some- 
times substituted  for  vesuvianite.  The 
first  has  a  greater  specific  gravity  and  is 
more  vivid  in  color,  and  the  latter  is  also 
heavier  and  harder. 

EUCLASE. 

Euclase  is  very  brittle,  and  therefore  is 
rarely  used  as  an  ornamental  stone. 

This  mineral  has  the  hardness  of  7.5  ; 
specific  gravity,  3.1  ;  lustre,  vitreous  to 
pearly ;  it  is  transparent  to  semi-trans- 
parent, doubly  refractive,  is  not  acted 
upon  by  acids,  fuses  under  the  blow-pipe 
to  a  white  enamel,  and  is  composed  of : 


IOO  PRECIOUS  STONES. 

Silica 41.2 

Alumina      ....  35.2 

Glucina 17.4 

Water 6.2 

Euclase  occurs  in  Brazil,  in  the  neigh- 
borhood  of  Villa  Rica,  and  also  in  the 
Urals,  in  -colorless,  pale  green,  blue,  pale 
yellow,  and  white  colors. 

SPHENE. 

Sphene  or  titanite  is  also  a  brittle 
mineral,  5  to  5.5  in  hardness ;  specific 
gravity,  3.4  to  3.56;  transparent,  doubly 
refractive ;  lustre,  adamantine  to  resinous ; 
colors,  brown,  gray,  yellow,  green,  black, 
and  colorless ;  and  composition  : 

Silica 31 

Titanium  oxide  .     .     .41 

Lime 27 

Ferrous  oxide      ...       I 

When  transparent  in  colorless,  green- 
ish, or  yellow  colors,  this  mineral  presents 
an  appearance  like  the  fire  opal. 

Sphene   is   found   in    Switzerland,   the 


PHENACITE.  101 

Urals,    Tyrol,    Finland,    Wales,    Ireland, 
Germany,  Canada,  and  the  United  States. 

PHENACITE. 

This  mineral,  rarely  used  as  a  gem 
stone,  is  7.5  to  8  in  hardness ;  specific 
gravity,  2.96  to  3  ;  lustre,  vitreous ;  trans- 
parent to  semi-translucent,  doubly  refrac- 
tive, it  does  not  melt  before  the  blow-pipe, 
and  contains : 

Silica 54.2 

Glucina 45.8 

Phenacite  occurs  colorless,  and  also 
bright  wine-yellow  inclining  to  red,  and 
brown.  This  stone  is  found  in  Russia, 
Mexico,  and  Alsace. 

The  colorless  or  transparent  variety  ap- 
proaches the  diamond  in  brilliancy,  espe- 
cially under  artificial  light. 

EPIDOTE. 

Epidote  usually  occurs  in  a  peculiar 
yellowish-green,  called  pistachio  green,  a 
color  that  is  seldom  found  in  other  min- 


IO2  PRECIOUS  STONES. 

erals.  Besides  this  color,  olive,  brown- 
ish-green,  greenish-black  and  black,  red, 
yellow-gray,  and  grayish-white  occur. 
The  hardness  of  epidote  is  6  to  7 ; 
specific  gravity,  3.32  to  3.50;  lustre,  vit- 
reous to  pearly  ;  refraction,  double.  The 
stone  is  transparent  to  opaque,  is  at- 
tacked by  acids,  and  is  slightly  affected 
by  the  blow-pipe.  It  is  composed  of : 

Silica 38 

Alumina 22 

Ferric  oxide  .     .     .     .  15 

Lime 23 

Water 2 

Epidote  is  found  in  Nonvay,  Saxony, 
Siberia,  Brazil,  on  the  St.  Gothard,  in 
Switzerland,  in  the  Tyrol,  and  in  the 
Hartz. 

AXINITE. 

Axinite  is  a  brittle  mineral  which  has 
occasionally  furnished  some  pretty  gem 
stones. 

The  hardness  of  this  stone  is  6.5  to  7 ; 
specific  gravity,  3.  to  3.3  ;  lustre,  vitreous. 
It  is  transparent  to  translucent,  is  not  at- 


DIOPSIDE.  IO3 

tacked  by  acids,  and  melts  readily  before 
blow-pipe.     It  is  composed  of  : 

Silica 43 

Lime 20 

Alumina 16 

Ferric  oxide 10 

Borontrioxide     ....  5 

Manganese  dioxide     .     .  3 

Magnesia 2 

Potash I 

Axinite  occurs  in  clove-brown,  plum- 
blue,  and  pearl-gray,  and  exhibits  trichro- 
ism.  The  best  specimens  come  from  St. 
Christophe  in  Dauphiny,  but  it  is  also 
found  at  Santa  Maria,  and  in  Switzer- 
land, Sweden,  England,  Chili,  Saxony,  the 
Hartz  Mountains,  and  the  United  States. 

Axinite  is  usually  cut,  like  the  opal, 
cabochon,  but  is  rarely  used  as  a  gem 
stone. 

DIOPSIDE. 

Diopside  is  cut  and  sometimes  sold  in 
Turin  and  in  Chamouny  as  a  gem  stone, 
but  no  great  quantity  of  this  mineral  is 
used  for  ornamental  purposes. 


IO4  PRECIOUS  STONES. 

The  hardness  of  diopside  is  5  to  6 ;  spe- 
cific gravity,  2.9  to  3.5  ;  lustre,  vitreous  to 
greasy.  It  is  transparent  to  translucent, 
brittle,  cannot  be  dissolved  by  acids,  and 
melts  before  the  blow-pipe.  It  is  com- 
posed of : 

Silica .....  54 

Lime  .....  24 

Magnesia      .     .     .  1 8 

Ferrous  oxide   .     .  4 

This  mineral  is  grayish-white  to  pearl- 
gray,  and  greenish-white  to  greenish-gray. 
The  best  green  transparent  specimens  are 
from  the  Mussa  Alp  and  Zillerthal,  but  it 
is  also  found  in  the  Urals  and  the  United 
States. 

FLUOR  SPAR. 

This  mineral  occurs  in  many  colors, 
often  approaching  the  finer  gems  in  ap- 
pearance, and  bearing  the  commercial 
names  of  false  ruby,  false  emerald,  false 
topaz,  etc.,  etc.,  according  to  its  color. 

Fluor  spar  is  brittle,  4  in  hardness,  has 
the  specific  gravity  of  3.1  to  3.2,  single 


HYPERSTHENE.  IO5 

refraction,  is  transparent  to  translucent, 
has  a  vitreous  lustre,  phosphoresces  when 
heated,  is  attacked  by  acids,  and  melts 
before  the  blow-pipe.  It  is  composed  of : 

Fluorine     .     .     48.7 
Calcium      .     .     51.3 

White,  yellow,  green,  rose-  and  crimson- 
red,  violet-blue,  sky-blue,  and  brown,  wine- 
yellow,  greenish-blue,  and  gray  are  the 
colors  of  this  many-tinted  mineral. 

Fluor  spar  is  found  in  England,  Nor- 
way, Baden,  Nova  Scotia,  Thuringia,  the 
Alps,  Saxony,  and  the  United  States. 

Large  pieces  of  this  mineral  are  made 
into  beautiful  vases  and  ornaments. 

HYPERSTHENE. 

Handsome  specimens  of  hypersthene  or 
Labrador  hornblende  are  used  for  orna- 
mental purposes. 

This  mineral  is  found  in  crystalline 
masses,  has  the  hardness  of  6,  specific 
gravity  3.3  to  3.4,  lustre  pearly  to  metal- 
lic. It  is  translucent  to  opaque,  brittle, 


IO6  PRECIOUS  STONES. 

and  fuses  before  the  blow-pipe.     It  con- 
sists of : 

Silica 54.2 

Magnesia     ....     24.1 
Protoxide  of  iron  .     .     21.7 

Hypersthene  occurs  in  dark-brown, 
green,  grayish-black,  greenish-black,  and 
jet-black  colors,  and  is  found  in  the  isle 
of  Skye,  the  Hartz  Mountains,  Saxony, 
Labrador,  Greenland,  Norway,  Sweden,  Bo- 
hemia, Thuringia,  and  the  United  States. 

QUARTZ. 

The  quartz  group  is  the  largest  and 
most  diversified  among  precious  stones. 
Quartz  occurs  massive,  in  concretions,  and 
in  confused  crystalline  masses. 

On  account  of  the  abundance  of  the 
massive  kinds,  such  as  jasper,  agates, 
onyx,  etc.,  some  writers  place  the  quartz 
group  under  the  head  of  semi-precious 
stones,and  lately  the  United  States  customs 
authorities  have  gone  further  in  that 
direction,  and  have  ruled  that  "  because 


QUARTZ.  IO7 

of  the  abundance  and  comparative  cheap- 
ness of  agates,  onyxes,  etc.,  they  were  no 
longer  precious  stones."  This  position, 
however,  the  custom-house  speedily  aban- 
doned, and,  for  dutiable  purposes  at  least, 
the  quartz  family,  in  all  its  ramifications, 
is  recognized  as  belonging  to  the  precious 
stones. 

Harder  than  the  tourmaline,  turquois, 
or  opal,  as  hard  as  the  chrysolite,  and 
nearly  as  hard  as  the  garnet  or  emerald, 
there  is  no  reason  why  the  crystallized 
varieties,  such  as  amethyst,  cairngorm, 
false  topaz,  chrysoprase,  and  even  the 
cat's-eye  and  finer  onyxes,  should  not  be 
classed  among  the  precious  stones. 

Some  more  plentiful  and  less  beautiful 
varities  of  quartz  are  not  valuable,  and 
they  take  the  same  position  in  the  quartz 
family  that  the  huge  imperfect  crystals  do 
in  the  beryl  group.  Whenever  the  speci- 
men is  sufficiently  beautiful  to  be  cut  and 
polished  for  setting  in  jewelry,  it  should 
be  included  under  the  precious  stones. 


IO8  PRECIOUS  STONES. 

Quartz  crystallizes  in  the  rhombohedral 
system,  and  many  varieties  are  found  mas- 
sive and  compact.  The  cleavage  is  indis- 
tinct but  can  sometimes  be  found  by 
plunging  a  heated  crystal  into  cold  water. 
The  hardness  of  quartz  is  7  ;  specific  grav- 
ity 2.5  to  2. 8,  the  purest  kinds  being  2.65  ; 
the  lustre  is  vitreous  to  resinous,  and 
fracture  conchoidal. 

Quartz  is  tough,  brittle,  and  feels  cold ; 
it  becomes  positively  electric  by  rubbing, 
shows  phosphorescence  in  the  dark,  and 
gives  sparks  if  struck  with  another  piece 
of  quartz  or  with  steel. 

Quartz  is  transparent  to  translucent, 
semi-translucent  to  opaque,  doubly  re- 
fractive, and  does  not  melt  before  the 
ordinary  blow-pipe,  but  may  be  melted 
with  the  oxyhydrogen  blow-pipe.  It  also 
melts  with  soda  to  a  clear  glass,  and  is 
soluble  in  fluohydric  acid. 

Quartz  is  composed  of  pure  silica 

Oxygen     .     .      53 
Silicon      .     .      47 


CRYSTALLIZED   QUARTZ.  1 09 

Some  of  the  impure  varieties  contain 
oxide  of  iron,  carbonate  of  lime,  clay,  and 
other  minerals. 

CRYSTALLIZED  QUARTZ. 

Colorless  quartz  or  pure  rock-crystal  is 
found  in  many  parts  of  the  world,  notably 
in  Switzerland,  Dauphiny,  Piedmont,  the 
Carrara  quarries  in  Italy,  Canada ;  in 
Herkimer  County,  New  York,  and  on  the 
shores  of  Lake  George,  in  the  same  place ; 
at  Hot  Springs,  Arkansas;  and  along 
the  beach  of  Long  Branch,  Cape  May, 
and  many  other  places. 

Rock-crystal,  commercially  known  as 
Bohemian  diamond,  occidental  diamond, 
Lake  George  diamond,  rhinestone,  pebble, 
etc.,  etc.,  is  colorless  and  transparent. 
This  stone  is  largely  used  for  optical  pur- 
poses, and  is  also  sometimes  cut  into  brill- 
iants to  imitate  the  diamond. 

While  rock-crystal  is  considerably  harder 
than  strass  or  paste,  it  lacks,  however,  the 
brilliancy  of  the  fine-composition  imitation 
diamond. 


110  PRECIOUS  STONES. 

Besides  being  much  softer,  the  paste  is 
often  heavier  than  the  crystal,  because  of 
the  quantity  of  lead  and  other  minerals 
used  in  its  composition. 

AMETHYST. 

Amethystine  quartz  or  amethyst  varies 
in  color  from  light  to  clear-dark  purple, 
sometimes  nearly  black,  and  from  light  to 
dark  bluish-violet.  The  coloring  of  the 
stone  is  supposed  to  be  due  to  manganese. 

The  best  amethysts  come  from  Brazil 
and  Ceylon,  but  good  specimens  are  found 
in  India,  Persia,  Botany  Bay,  Transylvania, 
near  Cork  and  the  island  of  May  in  Ireland, 
at  Oberstein,  in  Saxony,  in  Hungary, 
Siberia,  Nova  Scotia,  Sweden,  Bohemia, 
Canada,  and  in  the  States  of  Maine,  Penn- 
sylvania, Colorado,  Georgia,  Virginia,  and 
Michigan. 

Under  heat,  the  amethyst  turns  first 
yellow,  then  green,  and  finally  becomes 
colorless.  The  value  of  an  amethyst  de- 
pends upon  the  fashion,  and  the  time  has 


YELLOW  QUARTZ.  Ill 

been  when  these  stones  ranked  among  the 
most  valuable  of  precious  stones.  At 
present,  a  fine  amethyst  can  be  bought 
for  very  little  money,  but  should  the  stone 
become  fashionable  again,  the  best  speci- 
mens will  command  good  prices. 

YELLOW  QUARTZ. 

Yellow  quartz,  known  as  false  topaz, 
Bohemian,  occidental,  Indian,  or  Spanish 
topaz,  resembles  the  real  topaz  in  color, 
but  is  softer,  lighter,  different  in  crystal- 
lization and  cleavage,  and  in  electrical 
properties. 

In  color,  this  stone  varies  from  the  light- 
est yellow  to  orange-red  and  brown. 

Most  of  the  yellow  quartz  comes  from 
Brazil,  and  much  of  it  is  changed  to  yellow 
by  burning  amethyst  and  smoky  quartz. 

CAIRNGORM,  ETC. 

Smoky  yellow  to  smoky  brown,  often 
gray  and  black,  are  the  tints  of  the  cairn- 


112  PRECIOUS  STONES. 

gorm.  This  species  of  transparent  quartz 
takes  its  name  from  Cairngorm  in  Inver- 
nessshire,  in  Scotland,  a  locality  where 
some  of  the  best  specimens  have  been 
found.  Pike's  Peak,  Arkansas,  and  certain 
districts  in  North  Carolina  have  also  pro- 
duced some  very  fine  smoky  topazes. 

The  cairngorm  is  used  for  seals,  beads, 
and  some  of  the  cheaper  jewels,  and  is 
largely  sold  at  watering-places  in  Switzer- 
land, and  in  the  Western  United  Sates. 

The  stone  is  very  popular  in  Scotland. 
Hair  or  needle  stones  is  the  name  given 
to  these  varieties  of  crystallized  quartz 
when  they  contain  foreign  substances, 
such  as  rutile,  manganese,  chlorite,  etc.,  in 
hair  or  needle  formation. 

These  stones  are  cut  to  represent  the 
needle  enclosures  in  an  upright  position, 
and  are  called  sagenite  or  Venus  hair 
stones  or  love  arrows. 

Iridescent  or  rainbow  quartz  is  the 
variety  of  rock-crystal  containing  cracks 
and  fissures  which  reflect  all  the  colors  of 


ROSE   QUARTZ.  113 

the  rainbow.  Quartz  can  also  be  artifi- 
cially colored  by  rapidly  cooling  a  heated 
specimen  and  then  dipping  the  piece  into 
a  coloring  preparation ;  the  minute  cracks 
in  the  quartz  absorb  the  coloring  matter, 
and  the  result  is  a  red-,  blue-,  or  green- 
tinted  stone. 

The  massive  varieties  of  quartz  embrace 
the  rose  quartz,  avanturine,  cat's-eye,  cro- 
cidolite,  heliotrope,  chrysoprase,  prase, 
plasma,  chalcedony,  agates,  onyx,  car- 
nelian,  jasper,  hornstone,  and  flint. 

ROSE  QUARTZ. 

Rose  quartz  occurs  in  a  massive  form, 
usually  very  imperfect  and  cracked,  and 
varying  in  color  from  rose-red  to  pink. 
The  color  is  supposed  to  be  due  to  titanic 
acid,  and  often  becomes  paler  on  exposure. 

This  stone  is  nearly  opaque  and  semi- 
transparent  on  the  edges,  has  a  greasy 
lustre,  and  specific  gravity  of  2.65  to  2.75. 
Rabenstein  near  Zwiesel  in  Bavaria,  the 


114  PRECIOUS  STONES. 

United  States,  Brazil,  France,  Ceylon, 
Finland,  and  Siberia  are  places  where  rose 
quartz  has  been  found. 

AVANTURINE. 

Avanturine  is  an  opaque, yellow,  brown, 
or  red  quartz,  spangled  with  minute  scales 
of  mica  or  some  other  mineral,  and  found 
principally  near  Madrid,  in  Spain.  It  is 
also  found  in  France,  Scotland,  Bavaria, 
the  Urals,  and  Styria. 

A  beautiful  imitation  of  avanturine, 
called  goldstone,  is  manufactured  of  glass 
into  which  metal  filings  are  introduced. 
This  goldstone  is  superior  to  avanturine 
in  every  point  except  that  of  hardness. 
Avanturine  and  its  imitation,  but  largely 
the  latter,  are  used  for  the  cheaper  kinds 
of  jewelry,  and  were  very  popular  in  the 
United  States  some  years  ago. 

CAT'S-EYE. 

The  Hungarian,  occidental,  or  quartz 
cat's-eye  is  found  on  the  coast  of  Malabar, 
Ceylon,  Hartz  Mountains,  and  Bavaria. 


CROCIDOLITE.  1 1 5 

This  stone  is  translucent  to  opaque, 
gray,  green,  brown,  red,  and  the  shadings 
of  these  colors,  but  usually  a  greenish- 
gray,  with  a  mass  of  fine  white  lines  in 
the  centre,  which  give  to  the  stone  a 
chatoyant  appearance. 

The  cat's-eye  is  usually  cut  cabochon 
or  carbuncle-shaped,  and  the  lines  (which 
are  due  to  the  fibres  of  asbestos)  are  kept 
in  the  centre  of  the  stone,  and  play  like 
the  eye  of  a  cat  when  the  stone  is  moved. 

The  quartz  cat's-eye  is  easily  distin- 
guished from  the  oriental  of  chrysoberyl 
cat's-eye,  as  it  is  softer  and  much  lighter. 

CROCIDOLITE. 

Crocidolite  or  tiger-eye  is  a  light-brown, 
brownish-yellow  to  dark-green,  and  green- 
ish-blue quartz,  which  has  the  same 
chatoyant  qualities  as  the  cat's-eye.  When 
cut  cabochon,  the  crocidolite  is  called 
tiger-eye. 

This   beautiful    mineral  was   very  rare 


Il6  PRECIOUS  STONES. 

some  years  ago,  and  good  specimens  were 
sold  by  the  carat. 

Great  quantities,  however,  have  lately 
been  found  in  South  Africa,  and  although 
the  finest  pieces  are  still  used  for  cameos 
and  intaglios,  many  objects,  such  as  paper- 
weights, umbrella  handles,  match-safes, 
etc.,  are  now  cut  from  this  stone. 

Crocidolite  is  often  artificially  colored 
to  very  closely  imitate  some  of  the  finest 
shades  of  the  oriental  cat's-eye. 

HELIOTROPE. 

Heliotrope  or  blood-stone,  as  this  variety 
is  commonly  called,  is  a  dark-green  quartz, 
translucent  to  opaque,  and  covered  with 
small  red  spots  or  blood-colored  blotches, 
from  which  the  stone  derives  the  name  of 
blood-stone. 

This  stone  has  long  been  used  for  seal 
and  signet  purposes,  and  many  fine  in- 
taglios and  cameos  carved  in  blood-stone 
are  in  existence. 


CHR  YSOPRA  SE.  1 1 7 

Bucharia,  Tartary,  Siberia,  East  India, 
China,  the  island  of  Rum  in  the  Hebrides, 
the  United  States,  and  Canada  are  some 
of  the  places  where  the  heliotrope  is 
found. 

CHRYSOPRASE. 

The  chrysoprase  is  an  apple-green  chal- 
cedony, sometimes  olive-  or  whitish-green. 
It  is  translucent,  scratches  glass,  and  has 
the  specific  gravity  of  2.56. 

The  color  is  due  to  the  presence  of 
oxide  of  nickel.  This  stone  is  found 
principally  in  Silesia,  but  also  in  Siberia 
and  the  United  States. 

Large  pieces  of  chrysoprase  are  rare, 
and  even  the  best  specimens  lose  their 
color  in  course  of  time. 

PRASE. 

A  translucent,  spotted  leek-green,  green 
quartz,  which  loses  its  polish  on  exposure 
to  the  air,  is  known  as  prase. 

This  stone  is  found  principally  in  the 
iron  mines  of  Brietenbaum,  Saxony,  and 


Il8  PRECIOUS  STONES. 

also  in  Brittany,  the  Tyrol,  Scotland, 
Salzburg,  Finland,  and  the  United  States. 
Prase  is  sometimes  known  commercially 
as  "  mother  of  emerald,"  and  a  greenish 
crystalline  quartz  is  also  often  called  prase. 

PLASMA. 

Plasma  is  a  dark  grass-green  quartz, 
feebly  translucent,  and  is  sometimes  cov- 
ered with  white  or  yellow  spots.  Plasma 
is  somewhat  lighter  in  weight  than  the 
heliotrope  and  does  not  take  as  fine  a 
polish. 

This  stone  is  found  in  India,  China,  and 
in  the  Black  Forest,  Germany. 

CHALCEDONY. 

Chalcedony  is  cloudy  or  translucent, 
white,  yellowish-gray, blackish-brown,  light 
to  dark-blue,  milky-white,  and  black. 

This  quartz  is  sometimes  nearly  trans- 
parent, waxy  in  lustre,  and  in  some  varie- 
ties has  a  light  gray  and  transparent  base 
with  dark  cloudy  spots.  This  last  variety 


AGATES.  IIQ 

is  called  "  cloudy  chalcedony.  Another 
kind,  with  gray  and  white  stripes  alternat- 
ing, is  known  as  chalcedonyx. 

Iceland, -the  Faroe  Islands,  Huttenberg, 
Loben,  Saxony,  Hungary,  Nubia,  Nova 
Scotia,  Oberstein,  Ceylon,  India,  Siberia, 
Carinthia,  the  Hebrides,  the  United  States, 
and  Canada  are  places  where  chalcedony 
is  found. 

AGATES. 

Agate  is  an  improved  variety  of  chal- 
cedony and  comprises  the  following  kinds. 

Banded  or  ribbon  agate,  running  in  deli- 
cate parallel  layers. 

Eye  agate,  forming  concentric  rings 
with  a  dark  centre,  giving  the  appearance 
of  a  human  eye. 

Fortification  agate,  running  in  circular 
parallel  zigzag  lines  like  the  walls  of  a 
fortress. 

Rainbow  agate  is  a  thin  or  concentric 
structure  which  when  cut  across  and  held 
towards  the  light  shows  an  iridescence. 


I2O  PRECIOUS  STONES. 

Moss  agate,  light-gray  to  white  and 
translucent  to  opaque  agates,  display  black 
tracings  like  fine  moss  or  trees.  Mocha  or 
tree  agates  are  covered  with  black,  brown, 
or  red  figures,  as  of  trees  and  plants. 

Beckite  or  silicified  coral  shells,  silici- 
fied  wood,  wood  agate,  wood  opal,  cloudy 
agate,  and  agate  jasper  are  some  of  the 
many  varieties  of  this  class. 

The  common  carnelians,  blood-stones, 
and  onyxes  are  usually  counted  among  the 
agates. 

Uruguay,  Brazil,  Oberstein,  Silesia, 
Surinam,  India,  Arabia,  Saxony,  Scotland, 
the  United  States,  and  Canada  are  the 
principal  places  where  agates  are  found. 

ONYX  OR  AGATE  ONYX. 

Onyx  is  a  variety  of  chalcedony  in  bands 
or  strata  of  white,  gray,  and  black,  trans- 
lucent to  opaque,  and  generally  found 
where  agates  abound. 

The  layers  or  bands  are  in  even  planes, 
and  the  colors,  white  and  black,  white  and 


ONYX  OR  AGATE   ONYX.  121 

brown,  or  brown,  white,  and  black,  alter- 
nate. This  stone  is  largely  used  for 
cameos,  the  base  being  usually  of  black  or 
brown,  and  the  engraved  or  upper  part 
white-  or  cream-colored. 

When  one  or  more  layers  are  of  car- 
nelian  or  sard,  the  stone  is  called  sard- 
onyx. Sard  is  a  rich  brown  color  inclin- 
ing to  red,  and  when  held  against  the 
light  shows  a  red  hue. 

Onyx  and  sard-onyx  are  often  artificially 
improved  by  boiling  the  stones  in  honey, 
oil,  or  sugar  water,  and  then  in  sulphuric 
acid.  The  acid  carbonizes  the  sugar  or 
oil  which  the  stone  has  absorbed  and 
gives  it  a  deeper  color. 

For  red,  protosulphate  of  iron  is  added, 
and  for  a  blue  color  to  imitate  lapis 
lazuli,  yellow  prussiate  of  potash  is  added 
to  the  protosulphate  of  iron. 

Only  the  porous  parts  of  the  stones, 
usually  the  dark  parts,  absorb  the  sugar 
or  oil,  and  so  aid  the  contrast  of  the 
colored  with  the  white  layers. 


122  PRECIOUS  STONES. 

CARXELIAX. 

Carnelian  is  a  clear  red  translucent 
chalcedony,  and  is  usually  of  a  gray  or 
grayish-red  color.  Several  weeks  of  ex- 
posure to  the  sun's  rays  and  subsequent 
heating  in  earthen  pots  enhances  and 
deepens  the  color. 

The  brownish-red  or  dark-brown  car- 
nelian  is  called  sardoine  or  sard  ;  the 
blood-red  to  pink  varieties,  with  an  upper 
layer  of  white  onyx,  are  called  carnelian 
onyx,  and  the  stones  with  a  brown  or  sard 
base  and  a  white  top  are  called  sard-onyx. 

Carnelians  are  sometimes  of  a  yellowish- 
brown  or  yellow  color,  but  red  to  brown 
are  the  principal  colors. 

The  secret  of  coloring  agates  was  dis- 
covered in  the  early  part  of  this  century, 
and  about  the  same  time  agates  became 
scarce  in  Oberstein,  while  large  finds  were 
made  in  Brazil  and  Uruguay,  especially  of 
agates  with  red  layers.  This  variety 
comes  chiefly  from  Brazil. 

Besides  Uruguay  and   Brazil,   carnelian 


JASPER.  123 

is  found  in  Arabia  and  India.  The  most 
beautiful  specimens  of  intaglios  are  en- 
graved on  sardoine,  and  some  of  the  finest 
cameos  extant  are  of  sard  and  carnelian 
onyx. 

JASPER. 

Jasper  is  an  impure  opaque  quartz, 
usually  containing  more  iron  than  agate, 
and  lacking  the  quality  of  translucency. 
Jasper  occurs  in  red,  brown,  ochre-yellow, 
dark  green,  brownish-green,  grayish-black, 
and  grayish-blue;  sometimes  containing 
bands  or  spots  or  quartz  formations,  and 
often  found  with  regular  zones  or  bands 
of  various  colors. 

Egyptian  jasper  or  Egyptian  pebbles 
are  names  given  to  varieties  that  are 
usually  brown  with  inner  bands  of  lighter 
hue,  approaching  cream  in  color,  and 
sometimes  having  dark  bands  with  spots 
or  markings. 

Egyptian  jasper  is  found  near  Grand 
Cairo,  and  other  varieties  are  found  in  the 


124  PRECIOUS  STONES. 

Urals,  Saxony,  Devonshire,  Nova  Scotia, 
Canada,  and  the  United  States. 

The  specific  gravity  of  jasper  varies 
from  2.31  to  2.67;  it  scratches  glass,  but 
yields  to  rock-crystal. 

FALSE  LAPIS. 

False  lapis  is  jasper  or  agate  artificially 
colored  blue  to  imitate  the  true  lapis. 
Lapis  lazuli  is  softer  than  false  lapis,  being 
only  5  to  5.5  in  hardness. 

Sappharine  or  siderite  is  a  sapphire  or 
sky-blue  chalcedony  occurring  in  Saltz- 
burg. 

Nicolo  is  a  variety  of  onyx  with  a  black 
or  brown  base  and  a  band  or  layer  of 
bluish-white  on  top.  The  upper  layer  is 
not  flat,  but  convex,  and  is  always  thicker 
than  the  lower  one. 

HEMATITE. 

Hematite  was  once  largely  used  to  en- 
grave upon,  many  of  the  ancient  intaglios 
being  on  this  mineral.  It  is  now  cut  to 


OBSIDIAN.  125 

simulate  black  pearls,  and  is  also  used  in 
the  cheaper  jewelry,  both  engraved  and 
cut  cabochon. 

Hematite  has  the  hardness  of  5.5  to  6.5, 
and  specific  gravity,  4.2  to  5.3  ;  it  is  opaque, 
and  shows  a  red  streak  when  scratched.  It 
is  composed  of: 

Iron,     ...     70 
Oxygen,     .     .     30 

The  colors  of  hematite  are  dark-steel 
gray  to  iron-black,  and  sometimes  brown- 
ish- to  blood-red.  The  lustre  is  highly 
metallic,  with  slight  iridescence. 

The  island  of  Elba,  France,  Switzer- 
land, Italy,  Norway,  Sweden,  Bohemia, 
England,  Brazil,  Chili,  Canada,  Spain,  and 
the  United  States  are  places  where  hema- 
tite is  found.  The  Germans  call  this  min- 
eral "blood-stone,"  and  it  is  also  known 
as  specular  iron  ore  and  iron  glance. 

OBSIDIAN. 

Obsidian,  or  volcanic  glass,  does  not  oc- 
cupy a  high  position  as  a  gem  or  as  an 
ornamental  stone,  but  its  antiquity  and 


126  PRECIOUS  STONES. 

occasional  use  among  the  agates  and  semi- 
precious stones  will  justify  its  mention. 

This  mineral  is  a  melted  lava,  and  con- 
sists of  silex,  alumina,  and  a  little  potassa, 
soda,  and  oxide  of  iron.  Obsidian  is  6  to 
7  in  hardness,  has  a  specific  gravity  of 
2.25  to  2.8,  is  sometimes  transparent  but 
mostly  translucent  to  opaque,  and  is  vit- 
reous to  metallic  in  lustre.  It  is  brittle  and 
not  easily  attacked  by  acids.  It  melts  be- 
fore the  blow-pipe  and  takes  a  high  polish. 

Obsidian  comes  from  volcanoes,  and  is 
found  in  Iceland,  Teneriffe,  Lepare  is- 
lands, Peru,  Mexico,  Sicily,  and  on  all 
volcanoes.  The  color  is  velvety-black  to 
gray,  brown,  greenish-black,  yellow,  blue, 
bottle-green,  and  white,  seldom  red,  and 
often  with  black  or  yellow  spots  or 
veinings. 

Iceland  agate  lava,  volcanic  lava,  and 
royal  agate  are  all  obsidian. 

MALACHITE. 

Malacnite  although  sometimes  used  for 
jewelry,  is  now  more  largely  employed  for 


MALACHITE.  I2/ 

mosaic  work  and  ornamental  vases,  and  is 
sufficiently  costly  and  rare  to  be  classed 
amongst  the  precious  stones. 

Malachite  is  3.5  to  4  in  hardness ;  has  a 
specific  gravity  of  3.6  to  4;  is  translucent 
to  opaque  ;  the  lustre  is  vitreous  to  ada- 
mantine. It  is  attacked  by  acids,  and 
melts  before  the  blow-pipe.  It  is  com- 
posed of : 

Carbonic  acid     ...     20. 
Protoxide  of  copper     .     71.8 
Water 8. 

Malachite  occurs  in  emerald  or 
verdigris  green  color,  sometimes  in  al- 
ternating stripes  of  different  shades  of 
green,  and  occasionally  in  leek-  to  black- 
ish-green. 

Malachite  is  found  in  Russia,  France, 
the  Tyrol,  England,  Scotland,  Ireland, 
Germany,  Africa,  Chili,  Australia,  and  the 
United  States. 

The  finest  specimens  are  found  in  the 
Urals — a  block  three  and  a  half  feet  square, 
being  valued  at  525,000  roubles. 


128  PRECIOUS  STONES. 

JET. 

The  making  of  jet  or  mourning  jewelry 
was  once  a  very  large  industry  in  France 
and  England,  and  even  now  Whitby  jet  is 
well  known  in  commerce. 

Jet  is  a  species  of  bituminous  coal  (can- 
nel  coal)  which  can  be  cut  with  a  knife. 
The  hardness  is  I  to  2.5  ;  specific  gravity, 
1.35  ;  its  lustre  is  not  very  high,  and  color 
pitch-black. 

It  is  found  in  England,  France,  Hesse, 
Spain,  Italy,  and  Prussia. 

AMBER. 

Amber  is  a  fossil,  and  is  not  to  be  classed 
amongst  minerals,  but  this  material  has 
always  been  used  as  an  ornament,  and  a 
few  notes  will  not  be  out  of  place  here. 

This  vegetable  fossil,  which  has  been 
known  to  the  world  for  ages,  the  Greeks 
called  electron. 

It  is  very  light,  having  a  specific  gravity 
of  1.065  to  1.08,  and  is  2  to  2.5  in  hardness. 


AMBER.  129 

The  principal  color  is  yellow,  in  various 
shades,  sometimes  running  into  white  or 
reddish-brown  and  black. 

Amber  is  transparent  to  translucent, 
possesses  single  refraction,  a  resinous 
lustre  to  a  high  degree,  becomes  electric 
by  rubbing,  and  burns  readily  before  the 
blow-pipe. 

Amber  when  heated  becomes  soft  and 
pliable. 

Amber  is  composed  of: 

Carbon 79. 

Hydrogen      ....     10.5 
Oxygen 10.5 

Amber  is  imitated  by  gum  copal,  and 
even  the  insect  enclosures  which  occur  in 
real  amber  are  copied. 

These  imitations  can  be  detected  by 
placing  the  specimen  in  water  or  alcohol. 
This  is  also  a  good  test  for  pieces  of  real 
amber  that  have  been  melted  or  glued 
together. 

Amber  is  thrown  up  by  the  sea,  in  riv- 
ers near  the  sea,  or  on  the  sea-shore,  and 


I3O  PRECIOUS  STONES. 

has  been  found  in  nearly  all  parts  of  the 
world. 

The  Russian,  Baltic,  and  Sicilian  coasts 
have  yielded  the  larger  portion  of  the 
production,  but  supplies  come  also  from 
Galizia,  the  Urals,  Poland,  China,  and  the 
United  States. 

For  ornamental  purposes  the  faceted 
amber  beads  are  largely  used,  but  of  late 
years  these  have  been  closely  imitated 
in  glass. 

CORAL. 

Coral,  although  not  a  precious  stone, 
has  been  largely  used  in  jewelry,  and  as 
some  of  this  beautiful  substance  is  very 
valuable,  a  few  words  will  not  come  amiss. 

Red  or  precious  coral  is  the  work  of  a 
family  of  zoophytes  which  live  mostly  in 
cavities  of  rock  in  the  sea. 

These  polyps  build  their  homes  at  a 
depth  of  two  to  seven  hundred  feet 
under  the  surface  of  the  sea,  and  although 
the  single  groups  of  coral  are  sometimes 


CORAL.  131 

several  feet  long,  the  usual  size  is  about 
twelve  inches  high,  and  about  one  inch 
at  the  thickest  part  of  any  single  branch. 

Coral  is  usually  red,  and  rarely  white  or 
black,  while  the  pale  rose-pink  is  the 
most  esteemed  color. 

Coral  is  mostly  found  at  Calle,  off  the 
coast  of  Africa,  but  also  on  the  coasts  of 
Tunis,  Algiers,  Corsica,  Barbary,  Majorca, 
and  Minorca. 

Coral  fishing-vessels  leave  Italy  the  be- 
ginning of  March  and  return  from  the 
African  coast  in  October ;  at  one  time  as 
many  as  four  hundred  vessels  were  en- 
gaged in  this  industry. 


TABLE    OF    HARDNESS    AND    SPECIFIC 
GRAVITY. 


HARDNESS. 

SPECIFIC 
GRAVITY. 

Achroite       .... 
Alexandrite.     .     .     . 
Almandine  .... 
Almandite   .... 
Amber     ..... 

7-    —7-5 
8.5 
7-5 

7-5 

2       —  25 

3-        —3.1 

3.65     —3.8 

4-        —4-2 

4.      —  4.2 

I  065  —  I  08 

Apatite    

4-5  —  5« 

2.95    —  3-25 

Axinite              .          . 

6  «;  —  7 

3         —  33 

Beryl       

75  —  8. 

2  67    —  2  73 

Bobrowska  garnet  .     . 
Bohemian        "      .     . 
Brazilian  emerald  .     . 
1  '        sapphire 
Cachelong    .... 
Cat's-eye      .... 
Ceylon  chrysolite  .     . 
"      peridot.     .     . 
Chrysoberyl      .     .     . 
Chrysolite    .... 
Chrysoprase      .     .     . 
Cinnamon  stone    .     . 
Cyanite   

6. 

7-5 
7-    —7-5 
7-    —7-5 
5-5-6. 
8.5 
7-    —7-5 
7-    —7-5 
8-5 
6.5-7. 

6.5 

3.85 
3.69    —3.78 
3-        —3-i 
3-        —3-1 

2.           —  2.1 

3-        -  3-8 
3-        —3-1 
3-        —3-i 
3.65    —3-8 
3-3      —3-5 
2.56 
3-5      —3o6 
3-45    —  3-7 

Cymophane  .     ... 
Demantoide      .     .     . 
Diamond      .... 
Dichroite     .... 

8.5 
6. 

10. 

7-    —7-5 
5-    —6. 

3.65    —3.8 
3-85 
3-5      —3-6 
2.56    —  2.67 
2.0       —  3-5 

7.5  —  8. 

2.67     —  2.75 

Epidote             ... 

6.    —  7. 

3.32     —  3.50 

6.5 

3-5      —  3o6 

Euclase                   .     . 

7  5 

3.1 

Fluor  spar    .... 

4- 

3-1      —3-2 

132 


HA  RDNESS  A ND  SPE  CIFIC  GRA  VITY.    133 


HARDNESS. 

SPECIFIC 
GRAVITY. 

Garnet     

5     —  8 

315     —  A   -s 

Grossularite       .     .     . 
Hematite     .     .     .     . 
Hiddenite    .... 
Hyacinth      .... 
Hydrophane      .     .     . 
Hypersthene 

6-5 
5.6-6.5 
6-5  —  7. 
7-5 
5-5-6. 
6. 
6-5 

3-5      —3-56 
4-2      —5-3 
3.13    —3-19 
4-4      —4-7 

2.           —  2.1 

3-3      —3-4 
3-35    —  3  45 

Indicolite     .... 
Jacinth    

7-    —7-5 
7*5 

3-        —3-1 
4  4      —  4  7 

Targoon 

7e 

A    A                    A    7 

TasDer 

7 

2  31     —  2  67 

Jet      

2-5 

i  35 

Labrador      .... 
'  '       hornblende  . 
Lapis  lazuli  .... 
Malachite     .... 
Moonstone  .... 
Obsidian       .... 

6. 
6. 
5-    —5-5 
3.5  —  4. 
6.    —6.5 
6.    -7- 
6.5  —  7. 

2.62    —  2.76 

3-3      —3-4 
2.38    —  2.42 
3-6      —4. 
2.4      —  2.6 
2.25    —2.8 
3-3      —  35 

Opal  

55  —  6 

2            —  2 

Oriental  amethyst  .     . 
'  '        aquamarine  . 
chrysolite     . 
"        emerald  .     . 
"        hyacinth.     . 
"        topaz  .     .     . 
Pearl  
Peridot    .     . 

9. 
9- 
9- 
9- 
9- 
9- 

65  —  7 

3-9      —  4- 
3.9      —4. 
3-9      —4. 
3-9      —4- 
3-9      —  4- 
3-9      —4- 
2.5      —2.7 
33      —  35 

Phenacite     .... 
Pyrope 

7.5-8. 

7  ^ 

2.96    —3- 
3  69    —  3  78 

Quartz     ..... 

7 

25      —  2.8 

"      cat's-eye     .     . 
Rose  quartz  .... 
Rubellite      .... 
Ruby  

6.    —6.5 

7- 
7-    —7-5 
9- 

2.65 

2.65    —2.75 
3-        —3-1 
3-9      —  4-1 

'  '      cat's-eye  .     .     . 
Sapphire       .... 
"         cat's-eye.   . 

9- 
9- 
9- 

3-9      —4-1 
3-9      —4.1 
3-9      —4-1 

134 


PRECIOUS  STONES. 


HARDNESS. 

SPECIFIC 
GRAVITY. 

Siberite  

7. 
&'. 

6.5 
9- 
9- 
9- 
6. 

7-5 
S. 

6. 

7-5 
6.5 
7- 

—  7-5 

—  5-5 

—  7- 

—  7. 

—  5-5 
—  7-5 

—  7-5 

3- 
3-4 
3-5 
3-13 
3-9 

3-9 
3-9 
2.56 

4- 

3.4 
3-4 

2^6 

3-41 

3-35 
2.56 

-3-56 
—  3-6 
—  3.19 
—  4-1 
—  4.1 
—  4-1 
—  2.72 
—  4.42 
-3.56 
—  3-6 
—  3.1 

—  2.8 

—  3.52 
—  3-45 
-2.67 

Spinel     

Spodumene  .... 
Star  ruby      .... 
"    sapphire     .     .     . 
"    topaz     .... 
Sunstone      .... 
Syrian  garnet    .     .     . 
Titanite  

ToDaz 

Tourmaline  .... 
Turquois      .... 
Uwarowite  .... 
Vesuvianite  .... 
Water  sapphire      .     . 

GENERAL  INDEX. 


Achroite,  64 

Actinolite,  29 

Adularia,  see  moonstone 

Agate  jasper,  120 

Agate  onyx,  see  onyx 

Agate,  see  quartz,  106,  119,  122,  123,  124,  126 

Alexandrite,  8,  54,  56 

Almandine,  9,  30,  80 

Almandite,  29,  80 

Amazon  stone,  17,  88,  91 

Amber,  17,  28 

American  ruby,  80,  83 

Amethyst,  8,  9,  16,  17,  44,  49,  107,  no,  in 

Amethystine  quartz,  see  amethyst 

Antimony,  29 

Apatite,  19,  87 

Aquamarine,  8,  16,  53 

Aquamarine  chrysolite,  53 

Arizona  ruby,  80,  83 

Asterias,  see  star  sapphires 

Aurora  red  sapphire,  see  Oriental  hyacinth 

Avanturine   113,  114 

Avanturine  felspar,  see  sunstone 

Axinite,  17,  102 

Balas  ruby,  48 
Banded  agate,  119 

135 


136  PRECIOUS  STONES. 

Beckite,  120 

Beryl,  14,  16,  17,  44,  50,  52,  53,  87 

Blood-stone,  see  heliotrope 

see  hematite 

Bobrowska  garnet,  80,  83 
Bohemian  garnet,  80  82 

diamond,  see  rock-crystal 
"         topaz,  see  yellow  quartz 
Bone  turquois,  62 
Bort,  38 
Brazilian  aquamarine,  85 

"        emerald,  64,  67 

"        ruby,  85 

"        sapphire,  85 

"        topaz,  see  topaz 
Bronzite,  30 

Cachelong,  69,  70 
Cairngorm,  107,  ill 
Calcite,  19 
Cameo,  8 

Cannel  coal,  see  jet 
Cape  garnet,  80,  83 
Cape  ruby,  80,  83 
Carbon,  37 
Carbonate,  see  carbon 
Carbuncle,  So  83 
Carnelian,  17,  113,  123,  124 

"         onyx,  122 
Cat's-eye,  corundum,  8,  54,  57,  115,  116 

"         quartz,  18,  58,  107,  113,  114,  I  If 
Ceylon  cat's-eye,  see  corundum  cat's-eye 

"        chrysolite,  64,  79 

"       opal,  see  moonstone 
peridot,  64 


GENERAL  INDEX.  Itf 

Ceylonite,  47 

Chalcedonyx,  see  chalcedony 

Chalcedony,  8,  9,  16,  17,  113,  118,  119,  120,  122,  124 

Chrysoberyl  16,  17,  45,  54,  56,  57,  79 

Chrysolite,  17,  30,  53,  58,  78,  87,  99,  107 

Chrysoprase,  17,  107,  113,  117 

Cinnamon  stone,  see  grossularite 

Cleavage,  10 

Cloudy  agate,  120 

"       chalcedony,  see  chalcedony 
Colors,  1 6 
Coral,  130 

Cordierite,  see  dichroite 
Corundum,  9,  17,  39,  45,  47,  48,  49 
Crocidolite,  5,  18,  113,  115 
Crystallization,  10 
Cutting,  32 
Cyanite,  17.  92 
Cymophane,  54,  56,  57 

Decimal  system,  28 

Demantoide,  see  Bobrowska  garnet 

Diamond,  9,  n,  12,  14,  15,  17,  18,  20,  31,  32,  33,  35, 

40,  41,  49,  51,  52,  60,  75,  101,  109 
Dichroiscope,  14 
Dichroite,  97 
Diopside,  103 

Egyptian  jasper,  123 

pebbles,  see  Egyptian  jasper 
Electricity,  31 

Emerald,  8,  9,  16,  17,  18,  31,  44,  51,  87,  95,  107 
Epidote,  17,  101 
Essonite,  see  grossularite 


138  PRECIOUS  STONES. 

Euclase,  99 
Eye  agate,  119 

False  emerald,  see  fluor  spar 

"    lapis,  124 

' '    ruby,  see  fluor  spar 

"    topaz,  see  fluor  spar  and  yellow  quartz 
Fancy  sapphires,  44 
Felspar,  20,  88,  91 
Fish-eye,  see  moonstone 
Flint,  113 

Fluor  spar,  17,  19,  31,  104 
Fortification  agate,  119 
Fossil  turquois,  63 
Fracture,  n 
Fusibility,  28 

Garnet,  12,  14,  15,  17,  21,  32,  42,  53,  64,  107 

Girasol,  46 

Glass,  15 

Golden  beryl,  54 

Goldstone,  see  avanturine 

Goutte  d'eau,  85 

Green  felspar,  see  Amazon  stone 

<€     garnet,  80,  99 

"      sapphire,  see  Oriental  emerald 
Greenish-yellow  sapphire,  see  Oriental  chrysolite 
Grossularite,  30,  80,  82 

Hair-stone,  see  cairngorm 

Heliotrope,  113,  116,  118,  120 

Hematite,  18,  124 

Hiddenite,  95 

Hornstone,  113 

Hungarian  cat's-eye,  see  quartz  cat's-eye 


GENERAL  INDEX.  I3Q 

Hyacinth,  42,  58,  59 
Hydrophane,  69,  70 
Hypersthene,  105 

Iceland  lava,  see  obsidian 

"      spar,  14 
Idocrase,  17,  98 
Indian  topaz,  see  yellow  quartz 
Indicolite,  64,  67 
Intaglio,  8 
lolite,  see  dichroite 
Iridescent  quartz,  see  rose  quartz 

Jacinth,  58,  59,  82 
Jargoon,  58,  59 
Jaspar,  17,  106,  113,  123,  124 
Jet,  16,  128 

Labrador,  16,  88,  91 

' '        hornblende,  see  hypersthene 
Labradorite,  see  Labrador 
Labrador  spar,  see  Labrador 
Lake  George  diamond,  see  rock-crystal 
Lapis  lazuli,  17,  93,  124 
Lava,  see  obsidian 

Light-green  sapphire,  see  Oriental  aquamarine 
Love  arrows,  see  cairngorm 
Lustre,  17 

Magnetism,  30 

Malachite,  17,  127 

Mica,  ii 

Mineral  turquois,  61,  62 

Mocha  agate,  120 

Moonstone,  17,  38,  91,  109,  112 


140  PRECIOUS  STONES. 

Moss  agate,  120 

Mother  of  emerald,  see  prase 


Natrolite,  29 

Needle-stone,  see  cairngorm 
Nicolo,  124 


Obsidian,  10,  16,  125 
Occidental  cat's-eye,  see  quartz  cat's-eyc 
"         diamond,  see  rock-crystal 
"         topaz,  see  yellow  quartz 
"        turquois,  62 
Odontolite,  17,  62 
CEil  de  boeuf,  see  Labrador 
Oligoclase,  see  sun-stone 
Olivine,  17,  18,  53,  78,  84 
Onyx,  8,  106,  107,  113,  120,  124 
Opal,  8,  9,  10,  16,  17,  18,  30,  69,  100,  102,  107 
"     common,  see  opal 
"     fire,  "     " 

*'     noble,        "     " 
Opaline  felspar,  see  Labrador 
Oriental  amethyst,  39,  44 
"        aquamarine,  39,  44 
' '       chrysolite,  39,  44  ;  see  also  chrysobery! 
"       emerald,  39,  44,  51 
"       hyacinth,  39,  44 
"       opal,  see  opal 
"       topaz,  39,  44,  87 
"       turquois,  6 1 
Orthoclase,  29,  87 
Orthose,  see  moonstone 
Ox-eye,  see  Labrador 


GENERAL  INDEX. 

Pearl,  71 

"     baroque,  74 

"     black,  73,  124 

"     bouton,  74 

"     pink,  77 

Pebble  diamond,  see  rock-crystal 
Peridot,  16,  78 
Persian  turquois,  62 
Phenacite,  101 
Phosphorescence,  31 
Plasma,  113,  118 
PMochroism.  14 
Pleonast,  47 
Polarization  of  light,  13 
Polishing,  32 
Prase,  17,  113,  117,  118 
Precious  schorl,  see  tourmaline 
Purple  sapphire,  see  Oriental  amethyst 
Pyrope,  30,  80,  82 

Quartz,  9,  16,  20,  22,  42,  50,  106,  123 
"       cat's-eye,  see  cat's-eye  quartz 

Rainbow  agate,  119 
"         quartz,  112 
Reconstructed  rubies,  43 

turquois,  64 
Red  quartz,  see  quartz 
"    sapphire,  see  ruby 
Refraction,  12 
Rhinestone,  see  rock-crystal 
Ribbon  agate,  119 
Rock-crystal,  17,  3&,  91,  109,  112 

"     salt,  n,  19 
Rose  quartz,  17,  113 


142  PRECIOUS  STONES. 

Rose  topaz,  see  topaz 

Royal  agate,  see  obsidian 

Rubellite,  64,  65 

Rubicelle,  48 

Ruby,  14,  15,  16,  17,  18,  21,  26,  32,  37,  39,  40,  53,  64, 

107 

Ruby,  cat's-eye,  39,  46 
"      spinel,  see  spinel 

Saganite,  see  cairngorm 

Saphir  d'eau,  see  dichroite 

Sappare,  see  cyanite 

Sapphire,  16,  17,  20,  21,  37,  38,  39,  41,  42,  43,  51,  52, 

93,  98 

Sapphire,  cat's-eye,  39,  46 
Sapphirine,  48,  see  false  lapis 
Sard,  121,  122 
Sardoine,  see  saro 
Sardonyx,  121,  i?<* 
Saxony  topaz,  85 
Siberian  aquamarine,  53 

"        topaz,  8j> 
Siberite,  64 
Siderite,  see  false  lapis 
Silicified  coral  shells,  see  beckite 

"       wood,  1 20 
Slave's  diamond,  see  topaz 
Smoky-quartz,  see  cairngorm 

"      topaz,  16,  17 
Spanish  topaz,  see  yellow  quartz 
Specific  gravity,  21 
Sphene,  100 

Spinel,  12,  14,  15,  17,  18,  21,42,46 
Spodumene,  95,  96 
Star  ruby,  39,  45 


GENERAL  INDEX  143 

Star  sapphire,  39,  45 

"    topaz,  39,  45 
Streak,  18 

Sunstone,  46,  88,  89,  90 
Syrian  garnet,  80 

Talc,  19 

Titanite,  see  sphene 

Tiger-eye,  see  crocidolite 

Topaz,  8,  9,  16,  17,  20,  31,  32,  38,  42,  49,  50,  58,  84, 

107,  in 

Tourmaline,  13,  16,  17,  21,  32,  42,  53,  64,  107 
Transparency,  30 
Tree  agate,  see  Mocha  agate 
Turquois,  9,  10,  17,  18,  30,  60,  107 

Uwarowite,  80,  83 

Venus  hair-stone,  see  cairngorm 
Vermeille,  80,  83 
Vesuvianite,  see  idocrase 
Volcanic  glass,  see  obsidian 
"        lava,     "        " 

Water  opal,  see  moonstone 

"      sapphire,  see  dichroite 
Weight,  27 

White  spinel,  see  spinel 
Wood  agate,  120 

"      opal,  1 20 

Yellow  quartz,  in 

"       sapphire,  see  Oriental  topaz 

Zircon,  9,  16,  17,  18,  38,  49,  58 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

Los  Angeles 
This  book  is  DUE  on  the  last  date  stamped  below. 


JUL-8 


due  end  of 
Quarts 

Sffi*1* 


1976 


UD-URl 


JUN 


